[llvm] [LLVM] Specialize test suites for `TableGen` and `FileCheck` to use smaller set of dependencies (PR #155929)

[Sergei Barannikov via llvm-commits]

https://github.com/s-barannikov approved this pull request.

This PR is very useful for those who makes changes to llvm-tblgen. Without this change,  `ninja check-llvm-tablegen` rebuilds half of the project rather than just `FileCheck` and `llvm-tblgen`.

> The revised approach does not affect the fact that llvm-lit at startup looks at all tools and warns if some are missing. So we still get warnings about missing tools.

This is unfortunate, but I think we can sort it out later by adding lit config FileCheck/TableGen directories, if the warnings turn out to be annoying.


https://github.com/llvm/llvm-project/pull/155929