Mobile runtimeconfig.json support #49237

The goal here is to offer a fast, runtime-controlled mechanic for supporting arbitrary AppContext properties on mobile devices and potentially single file scenarios.

.NET6 :

• [mono] Propagate hosting properties through AppContext #37240 - [mono] Propagate hosting properties through AppContext
• Create msbuild task that generates binary runtimeconfig format #49235 - Create msbuild task that generates binary runtimeconfig format
• Add new Mono embedding API to consume binary runtimeconfig format #49236 - Add new Mono embedding API to consume binary runtimeconfig format
• Document new embedding API and MSBuild task
• Create a Nuget package for RuntimeConfigParser #51236 - Create a Nuget package for RuntimeConfigParserTask
• Add RuntimeConfigParserTask to the Mono workload pack #50906 - Add RuntimeConfigParserTask to the Mono workload pack
• Adopt in the Xamarin products (requires the nuget/workload pack)
  • Android
  • iOS
• WebAssembly should support handling runtimeconfig.json #38433
• Add a runtimeconfig.json test for WASM #50908 - Add a runtimeconfig.json test for WASM
• Replace ArgumentException with LogError for RuntimeConfigParser to be more user friendly #51232 - Replace ArgumentException with LogError for RuntimeConfigParser to be more user friendly

Future milestone :

• Create a new test, instead of adding runtimeconfig.json to the existing Android functional test #50905 - Create a new test, instead of adding runtimeconfig.json to the existing Android functional test