fix: TypeError when trying to use bin-scripts in Python (#2720)

### Problem
Bin script on Python is failing with error `The "path" argument must be of type string. Received undefined`

### Solution
- Changed parameter name `pkgname` on `assembly` in `InvokeScriptRequest`
- Returned response from `invokeBinScript` (used for printing output)

### Testing
Running bin script with these change and make sure that bin scripts are running.

packages/@jsii/python-runtime/src/jsii/_kernel/__init__.py

@@ -35,6 +35,7 @@
  InvokeRequest,
  InvokeResponse,
  InvokeScriptRequest,
+ InvokeScriptResponse,
  KernelResponse,
  LoadRequest,
  ObjRef,
@@ -254,13 +255,13 @@ def load(self, name: str, version: str, tarball: str) -> None:
 
  def invokeBinScript(
  self, pkgname: str, script: str, args: Optional[List[Any]] = None
- ) -> None:
+ ) -> InvokeScriptResponse:
  if args is None:
  args = []
 
- self.provider.invokeBinScript(
+ return self.provider.invokeBinScript(
  InvokeScriptRequest(
- pkgname=pkgname,
+ assembly=pkgname,
  script=script,
  args=_make_reference_for_native(self, args),
  )

packages/@jsii/python-runtime/src/jsii/_kernel/types.py

@@ -44,7 +44,7 @@ class LoadResponse:
 @attr.s(auto_attribs=True, frozen=True, slots=True)
 class InvokeScriptRequest:
 
- pkgname: str
+ assembly: str
  script: str
  args: List[Any] = attr.Factory(list)
 
@@ -55,7 +55,7 @@ class InvokeScriptResponse:
  status: int
  stdout: str
  stderr: str
- output: List[str]
+ signal: str
 
 
 @attr.s(auto_attribs=True, frozen=True, slots=True)