`prop.Value.GetRawText ()` returns a string value `foo` as `"foo"`.

Let's instead switch on `JsonValueKind` and handle each type
appropriately.

The existing `AppContextTests` should verify this when we enable the
`RuntimeConfig` category.

#10666)

Test randomly fails with:

    (_MavenRestore target) ->
       Xamarin.Android.Bindings.Maven.targets(28,5): error XA4236: Cannot download Maven artifact 'androidx.core:core'.
       Xamarin.Android.Bindings.Maven.targets(28,5): error XA4236: - core-1.9.0.jar: Response status code does not indicate success: 404 (Not Found).
       Xamarin.Android.Bindings.Maven.targets(28,5): error XA4236: - core-1.9.0.aar: The process cannot access the file 'C:\Users\cloudtest\AppData\Local\dotnet-android\MavenCacheDirectory\google\androidx.core\core\1.9.0\core-1.9.0.aar' because it is being used by another process.

Let's make this `Assert.Inconclusive()`.

I also fixed where the test wasn't building the `collection` project.

This test is flaky, but it currently has a terrible error message as "1":

    Mono.Android.NET_Tests, Xamarin.Android.NetTests.AndroidMessageHandlerIntegrationTests.HttpClientIntegrationTestBase.CancelRequestViaProxy / Debug
    Error message
       1
    Stack trace
       at Xamarin.Android.NetTests.HttpClientIntegrationTestBase.CancelRequestViaProxy() in /Users/runner/work/1/s/tests/Mono.Android-Tests/Mono.Android-Tests/Xamarin.Android.Net/HttpClientIntegrationTests.cs:line 166
       at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
       at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)

Let's improve the assertion message, in general, and that might help
diagnose the flakiness in the future.

This shouldn't alter the behavior of the test, just the assertion message.

…10670)

Context: https://github.com/dotnet/runtime/blob/242f7b23752599f22157268de41fee91cb97ef6c/docs/design/features/host-startup-hook.md

.NET has a concept of a "startup hook", which appears to work fine
on Mono if you set:

    env.txt
        DOTNET_STARTUP_HOOKS=StartupHook
    (MSBuild)
        <StartupHookSupport>true</StartupHookSupport>
        <RuntimeHostConfigurationOption Include="STARTUP_HOOKS" Value="StartupHook" />

The startup hook is a managed assembly with a static method, in the
"global" namespace:

    class StartupHook
    {
        public static void Initialize()
        {
            // ...
        }
    }

When the runtime starts, it will call `StartupHook.Initialize()` before
any other managed code is executed.

`dotnet watch` (Hot Reload) relies on this feature.

I added tests to verify startup hooks are called on Android for
all runtimes.

* [coreclr] call `System.StartupHookProvider.ProcessStartupHooks()`

This feature only works on CoreCLR if you have a `static void Main()`,
which we do not on Android. For now, I called the `StartupHookProvider`
directly with System.Reflection. We can address in dotnet/runtime
in the future.

Context: https://r8.googlesource.com/r8/+/refs/tags/8.13.19
Context: https://maven.google.com/web/index.html?q=r8#com.android.tools:r8:8.13.19