ci: formatter benchmarks

[ematipico]

Summary

This PR is part of #1996
Closes #2030

I creates a new workflow to run the formatter against the libraries that we use to bench the parser.

I changed the key comments to trigger the benchmarks:

• !bench_parser will trigger the parser benchmarks
• !bench_formatter will trigger the formatter benchmarks
• the old alias cargo benchmark has been removed
• new cargo alias called cargo bench_parser
• new cargo alias called cargo bench_formatter

Test Plan

Existing CI and run locally the new command.

[ematipico]

@MichaReiser @leops I update the description of the issue and applied your suggestions