The AndroidAppBuilder was incorrectly looking for {ProjectName}.runtimeconfig.json when the actual generated file is named {AssemblyName}.runtimeconfig.json, causing the CoreCLR Android test host to fail finding the runtime configuration file.

Problem

When building Android apps and especially when running tests:

• The assembly name differs from the project name
• For tests, mainLibraryFileName is set to AndroidTestRunner.dll
• Looking for AndroidTestRunner.runtimeconfig.json for all tests is incorrect as each test project has its own configuration
• This resulted in errors like: Could not find file 'HelloAndroid.runtimeconfig.json'

Solution

Modified the ParseRuntimeConfigProperties method to use the standardized runtimeconfig.bin file instead of trying to guess the correct JSON filename. This binary file is created by MSBuild's RuntimeConfigParserTask and contains the same configuration properties in a binary format.

The implementation uses the existing BlobReader from System.Reflection.Metadata to read the binary format, which provides the necessary ReadCompressedInteger() and ReadSerializedString() methods that mirror the BlobBuilder write operations.

Before:

string runtimeConfigPath = Path.Combine(AppDir, $"{ProjectName}.runtimeconfig.json");

After:

string runtimeConfigPath = Path.Combine(AppDir, "runtimeconfig.bin");

The solution maintains the same functionality of extracting configProperties for the CoreCLR Android template while working reliably for both apps and test scenarios.

Fixes #118162.

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