[Microsoft.Android.Sdk.ILLink] fix crash when TZ changes

[jonathanpeppers]

Fixes: #7953

When a timezone changes in a Release app, it can crash with:

[monodroid] Unable to find Android.Runtime.AndroidEnvironment.NotifyTimeZoneChanged()!

In 11f0e1b, we removed the line:

<?xml version="1.0" encoding="utf-8" ?>
<linker>
    <assembly fullname="Mono.Android">
--      <type fullname="Android.Runtime.AndroidEnvironment" />

Unfortunately, this method is called from native code, so we need to always preserve it.

Added a test for this scenario, we may want to audit all mono_class_get_method_from_name calls and add more tests cases.

I also cleaned up the tests a bit with a getResource() local function.

[jonathanpeppers]

Ok new test failed as expected:

04-12 22:57:44.275 11569 11569 I XALINKERTESTS: [FAIL] PreserveTest.MethodsArePreserved FAILED: System.NullReferenceException: Object reference not set to an instance of an object
04-12 22:57:44.275 11569 11569 I XALINKERTESTS:    at PreserveTest.MethodsArePreserved()

Let me change it so it isn't an NRE, and then put the fix in.

[jonathanpeppers]

Looks like the new test is green now, the only test failure is odd, but probably unrelated:

                   (_Upload target) -> 
                     /Users/runner/work/1/s/xamarin-android/bin/Release/dotnet/packs/Microsoft.Android.Sdk.Darwin/34.0.0-ci.pr.gh7956.249/tools/Xamarin.Android.Common.Debugging.targets(623,5): error XA0137: The 'run-as' command failed with 'run-as: couldn't stat /data/user/11/com.xamarin.applicationrunswithdebuggerandbreaks: No such file or directory'. [/Users/runner/work/1/a/TestRelease/04-13_14.33.17/temp/ApplicationRunsWithDebuggerAndBreaksFalseAssembliesFalseguest1/App/App.csproj]
                   /Users/runner/work/1/s/xamarin-android/bin/Release/dotnet/packs/Microsoft.Android.Sdk.Darwin/34.0.0-ci.pr.gh7956.249/tools/Xamarin.Android.Common.Debugging.targets(623,5): error XA0137: Fast Deployment is not currently supported on this device. [/Users/runner/work/1/a/TestRelease/04-13_14.33.17/temp/ApplicationRunsWithDebuggerAndBreaksFalseAssembliesFalseguest1/App/App.csproj]
                   /Users/runner/work/1/s/xamarin-android/bin/Release/dotnet/packs/Microsoft.Android.Sdk.Darwin/34.0.0-ci.pr.gh7956.249/tools/Xamarin.Android.Common.Debugging.targets(623,5): error XA0137: Please file an issue with the exact error message using the 'Help->Send Feedback->Report a Problem' menu item in Visual Studio [/Users/runner/work/1/a/TestRelease/04-13_14.33.17/temp/ApplicationRunsWithDebuggerAndBreaksFalseAssembliesFalseguest1/App/App.csproj]
                   /Users/runner/work/1/s/xamarin-android/bin/Release/dotnet/packs/Microsoft.Android.Sdk.Darwin/34.0.0-ci.pr.gh7956.249/tools/Xamarin.Android.Common.Debugging.targets(623,5): error XA0137: or 'Help->Report a Problem' in Visual Studio for Mac. [/Users/runner/work/1/a/TestRelease/04-13_14.33.17/temp/ApplicationRunsWithDebuggerAndBreaksFalseAssembliesFalseguest1/App/App.csproj]
                   /Users/runner/work/1/s/xamarin-android/bin/Release/dotnet/packs/Microsoft.Android.Sdk.Darwin/34.0.0-ci.pr.gh7956.249/tools/Xamarin.Android.Common.Debugging.targets(623,5): error XA0137: Please set the 'EmbedAssembliesIntoApk' MSBuild property to 'true' to disable Fast Deployment in the Visual Studio project property pages, or edit the project file in a text editor. [/Users/runner/work/1/a/TestRelease/04-13_14.33.17/temp/ApplicationRunsWithDebuggerAndBreaksFalseAssembliesFalseguest1/App/App.csproj]