Add warning wave support and warn for unnecessary `@` in component parameters

[jjonescz]

Resolves https://github.com/dotnet/razor/issues/9740. Related (internal): https://github.com/dotnet/Razor-Language-Design/discussions/5 Commit-by-commit review might be useful.

The warning waves feature needs an SDK counterpart change to fully work (prototype here: https://github.com/dotnet/sdk/pull/40720), but it shouldn't need any coordinated merging - without the SDK passing RazorWarningLevel through, the warnings simply stay disabled.