Make parallel compilation features work with deterministic builds

[majocha]

Currently only parallel reference resolution is supported. (see #18998)

The following do not work and are automatically disabled for deterministic builds:

• Parallel ILX Gen
• Graph based type checking (dedicated issue: Make graph-based type-checking fully deterministic and do not auto-disable it in deterministic builds. #14734)
• Parallel Optimizations

According to comments #14390 (comment) The issue most probably lies in embedded PDB generation.

Name generation in CompilerGlobalState.fs does not play well with parallel compilation, too.

[majocha]

I'll gather some relevant comments here: #14390 (comment)

[majocha]

The saga of graph type checking determinism is scattered among many PRs that I wasn't paying much attention to at the time. I'm only getting up to speed now. It seems at some point it worked / almost worked? (#15003)

Also #14850