unblocks manually triggered tsgo server tests

[iisaduan]

Uses the structure @gabritto set up for the fuzzer to allow manually triggered "tsserver" user tests to run (aka test tsserver top###)

I decided to continue calling them "tsserver" for the ENTRYPOINT parameter for simplicity, so that the pipeline (and bot) need less changes. The two entrypoint parameters continue to be tsc and tsserver, and if it's tsserver, the correct lsp vs tsserver infrastructure is chosen based on if we're testing tsgo or not.

(I'm also open to not doing that and making the changes in the pipeline interface/bot call to explicitly specify lsp or have them be aliases, etc, but I didn't have super strong opinions either way)

I don't believe this conflicts with/doubles up anything included in #210

[gabritto]

Why do we need this after #210? I renamed the lsp entrypoint to fuzzer to make it clear what that entry point is supposed to do in my mind: run the latest TS version to find errors, without comparing two different versions. So the typical entry points to compare two versions would remain "tsc" or "tsserver". Open to suggestions on naming though.

[iisaduan]

I think I misunderstood the totality of what #210 was renaming