Convert genRuntimeEventSources to a C# source generator

[jkoritzinsky]

Convert this script to C# to remove the only direct python usage from within our managed build.

I primarily converted this script with VSCode's Copilot's Agent mode with ChatGPT 4.1, with a few logic adjustments as necessary to match the python script's codegen.

[Copilot]

Pull Request Overview

This PR converts a Python-based code generation script into a C# source generator to remove a direct Python dependency from our managed build.

• Converts the logic for manifest file processing and event method generation from Python to C#.
• Adopts Roslyn incremental generator APIs, new string interpolation with raw strings, and modern collection initialization.

Files not reviewed (5)

• eng/python.targets: Language not supported
• src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj: Language not supported
• src/coreclr/nativeaot/System.Private.CoreLib/src/System.Private.CoreLib.csproj: Language not supported
• src/libraries/System.Private.CoreLib/gen/System.Private.CoreLib.Generators.csproj: Language not supported
• src/mono/System.Private.CoreLib/System.Private.CoreLib.csproj: Language not supported

[am11]

Nice! genLttngProvider etc. can also be converted to src/native/minipal/UnicodeDataGenerator type of a generator with output native code checked in, as the output unicodedata.c rarely changes (and when they do,Updating-Unicode-Versions.md has steps how to update).