[llvm] Add a pass to convert jump tables to switches. (PR #77709)

[Alexander Shaposhnikov via llvm-commits]

alexander-shaposhnikov wrote:

@david-xl - correct, to the best of my knowledge libc++ tried to change the implementation in the past but then moved back.
I thought about revisiting it again, however, since this is not specific to std::variant rewriting other libraries is unfeasible.

https://github.com/llvm/llvm-project/pull/77709