[llvm] [BOLT] Setup CDSplit Pass Structure (PR #73079)

[via llvm-commits]

ShatianWang wrote:

Note: this PR is 3/8 for upstreaming a new 3-way (hot-warm-cold) function splitting algorithm CDSplit.
It is one commit ahead of #73078

https://github.com/llvm/llvm-project/pull/73079