[wasm] Re-enable source generator tests failing due to OOM (#60701)

[wasm] Re-enable source generator tests failing due to OOM (#60701)

This adds support for setting per-project optimization flags, and sets them for these projects so they don't OOM.

Microsoft.Extensions.Logging.Generators.Roslyn3.11.Tests
Microsoft.Extensions.Logging.Generators.Roslyn4.0.Tests
System.Text.Json.SourceGeneration.Roslyn3.11.Unit.Tests
System.Text.Json.SourceGeneration.Roslyn4.0.Unit.Tests
System.Text.RegularExpressions.Generators.Tests
Some individual ones are disabled due to
#58226, and #60899 .

Additionally, if a AOT build fails, then on linux it dumps the last few lines from dmesg, to help identify it was an oom-kill.

Fixes #51961 .

Co-authored-by: Larry Ewing <lewing@microsoft.com>