[lldb] Return unimplemented error from ScriptedProcessInterface::CreatePluginObject

After llvm#68052 this function changed from returning
a nullptr with `return {};` to returning Expected and hitting `llvm_unreachable` before it could
do so.

I gather that we're never supposed to call this function, but on Windows we actually do call
this function because `interpreter->CreateScriptedProcessInterface()` returns
`ScriptedProcessInterface` not `ScriptedProcessPythonInterface`. Likely because
`target_sp->GetDebugger().GetScriptInterpreter()` also does not return a Python related class.

The previously XFAILed test crashed with:
```
 # .---command stderr------------
 # | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
 # | Stack dump:
 # | 0.  Program arguments: c:\\users\\tcwg\\david.spickett\\build-llvm\\bin\\lldb-test.exe ir-memory-map C:\\Users\\tcwg\\david.spickett\\build-llvm\\tools\\lldb\\test\\Shell\\Expr\\Output\\TestIRMemoryMapWindows.test.tmp C:\\Users\\tcwg\\david.spickett\\llvm-project\\lldb\\test\\Shell\\Expr/Inputs/ir-memory-map-basic
 # | 1.  HandleCommand(command = "run")
 # | Exception Code: 0xC000001D
 # | #0 0x00007ff696b5f588 lldb_private::ScriptedProcessInterface::CreatePluginObject(class llvm::StringRef, class lldb_private::ExecutionContext &, class std::shared_ptr<class lldb_private::StructuredData::Dictionary>, class lldb_private::StructuredData::Generic *) C:\Users\tcwg\david.spickett\llvm-project\lldb\include\lldb\Interpreter\Interfaces\ScriptedProcessInterface.h:28:0
 # | #1 0x00007ff696b1d808 llvm::Expected<std::shared_ptr<lldb_private::StructuredData::Generic> >::operator bool C:\Users\tcwg\david.spickett\llvm-project\llvm\include\llvm\Support\Error.h:567:0
 # | #2 0x00007ff696b1d808 lldb_private::ScriptedProcess::ScriptedProcess(class std::shared_ptr<class lldb_private::Target>, class std::shared_ptr<class lldb_private::Listener>, class lldb_private::ScriptedMetadata const &, class lldb_private::Status &) C:\Users\tcwg\david.spickett\llvm-project\lldb\source\Plugins\Process\scripted\ScriptedProcess.cpp:115:0
 # | #3 0x00007ff696b1d124 std::shared_ptr<lldb_private::ScriptedProcess>::shared_ptr C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1478:0
 # | #4 0x00007ff696b1d124 lldb_private::ScriptedProcess::CreateInstance(class std::shared_ptr<class lldb_private::Target>, class std::shared_ptr<class lldb_private::Listener>, class lldb_private::FileSpec const *, bool) C:\Users\tcwg\david.spickett\llvm-project\lldb\source\Plugins\Process\scripted\ScriptedProcess.cpp:61:0
 # | #5 0x00007ff69699c8f4 std::_Ptr_base<lldb_private::Process>::_Move_construct_from C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1237:0
 # | llvm#6 0x00007ff69699c8f4 std::shared_ptr<lldb_private::Process>::shared_ptr C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1534:0
 # | llvm#7 0x00007ff69699c8f4 std::shared_ptr<lldb_private::Process>::operator= C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1594:0
 # | llvm#8 0x00007ff69699c8f4 lldb_private::Process::FindPlugin(class std::shared_ptr<class lldb_private::Target>, class llvm::StringRef, class std::shared_ptr<class lldb_private::Listener>, class lldb_private::FileSpec const *, bool) C:\Users\tcwg\david.spickett\llvm-project\lldb\source\Target\Process.cpp:396:0
 # | llvm#9 0x00007ff6969bd708 std::_Ptr_base<lldb_private::Process>::_Move_construct_from C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1237:0
 # | llvm#10 0x00007ff6969bd708 std::shared_ptr<lldb_private::Process>::shared_ptr C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1534:0
 # | llvm#11 0x00007ff6969bd708 std::shared_ptr<lldb_private::Process>::operator= C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1594:0
 # | llvm#12 0x00007ff6969bd708 lldb_private::Target::CreateProcess(class std::shared_ptr<class lldb_private::Listener>, class llvm::StringRef, class lldb_private::FileSpec const *, bool) C:\Users\tcwg\david.spickett\llvm-project\lldb\source\Target\Target.cpp:215:0
 # | llvm#13 0x00007ff696b13af0 std::_Ptr_base<lldb_private::Process>::_Ptr_base C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1230:0
 # | llvm#14 0x00007ff696b13af0 std::shared_ptr<lldb_private::Process>::shared_ptr C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1524:0
 # | llvm#15 0x00007ff696b13af0 lldb_private::PlatformWindows::DebugProcess(class lldb_private::ProcessLaunchInfo &, class lldb_private::Debugger &, class lldb_private::Target &, class lldb_private::Status &) C:\Users\tcwg\david.spickett\llvm-project\lldb\source\Plugins\Platform\Windows\PlatformWindows.cpp:495:0
 # | llvm#16 0x00007ff6969cf590 std::_Ptr_base<lldb_private::Process>::_Move_construct_from C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1237:0
 # | llvm#17 0x00007ff6969cf590 std::shared_ptr<lldb_private::Process>::shared_ptr C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1534:0
 # | llvm#18 0x00007ff6969cf590 std::shared_ptr<lldb_private::Process>::operator= C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.35.32124\include\memory:1594:0
 # | llvm#19 0x00007ff6969cf590 lldb_private::Target::Launch(class lldb_private::ProcessLaunchInfo &, class lldb_private::Stream *) C:\Users\tcwg\david.spickett\llvm-project\lldb\source\Target\Target.cpp:3274:0
 # | llvm#20 0x00007ff696fff82c CommandObjectProcessLaunch::DoExecute(class lldb_private::Args &, class lldb_private::CommandReturnObject &) C:\Users\tcwg\david.spickett\llvm-project\lldb\source\Commands\CommandObjectProcess.cpp:258:0
 # | llvm#21 0x00007ff696fab6c0 lldb_private::CommandObjectParsed::Execute(char const *, class lldb_private::CommandReturnObject &) C:\Users\tcwg\david.spickett\llvm-project\lldb\source\Interpreter\CommandObject.cpp:751:0
 # `-----------------------------
 # error: command failed with exit status: 0xc000001d
```

That might be a bug on the Windows side, or an artifact of how our build is setup,
but whatever it is, having `CreatePluginObject` return an error and
the caller check it, fixes the failing test.

The built lldb can run the script command to use Python, but I'm not sure if that means
anything.

Author: DavidSpickett

lldb/include/lldb/Interpreter/Interfaces/ScriptedProcessInterface.h

@@ -12,6 +12,7 @@
 #include "ScriptedInterface.h"
 #include "lldb/Core/StructuredDataImpl.h"
 #include "lldb/Target/MemoryRegionInfo.h"
+#include "lldb/Utility/UnimplementedError.h"
 
 #include "lldb/lldb-private.h"
 
@@ -25,8 +26,7 @@ class ScriptedProcessInterface : virtual public ScriptedInterface {
   CreatePluginObject(llvm::StringRef class_name, ExecutionContext &exe_ctx,
                      StructuredData::DictionarySP args_sp,
                      StructuredData::Generic *script_obj = nullptr) {
-    llvm_unreachable(
-        "Cannot create an instance of the ScriptedProcessInterface!");
+    return {llvm::make_error<UnimplementedError>()};
   }
 
   virtual StructuredData::DictionarySP GetCapabilities() { return {}; }

lldb/test/Shell/Expr/TestIRMemoryMapWindows.test

@@ -1,5 +1,4 @@
 # REQUIRES: system-windows
-# XFAIL: system-windows
 
 # RUN: %clang_cl_host /Zi /GS- %p/Inputs/call-function.cpp /c /o %t.obj
 # RUN: %msvc_link /debug:full %t.obj /out:%t