Setup the performance dashboard and Regular Benchmark Tests for all language Emitters

We currently lack of data for all TypeSpec emitter performance, especially at large Resource Provider (RP)
Possible performance regressions are only detected after developers experience slow execution time.
This makes it hard to proactively detect, debug, and prevent performance issues

So we need:
- Clear performance baselines and trends to detect regressions early.
- Regular, automated performance tests running as part of scheduled jobs.
- Dashboard for visibility for language emitters, including large RP scenarios.

Start by surveying the repository for existing emitter performance benchmarks, scheduled workflows, and dashboard configuration; the issue names no files or tests. Determine how large Resource Provider scenarios and each language emitter should be measured, where results should be stored, and what scheduled-job output defines a detected regression. Done means recurring benchmarks, baseline and trend visibility, and coverage for the requested emitters and large RP cases.

Written by the indexing model from the issue text.