[llvm] [KnownBits] Add fast path for udiv by pow2 and overloads for shift ops by constant (PR #189779)

[Max Graey via llvm-commits]

MaxGraey wrote:

> There are some places in ScalarEvolution's getRangeForUnknownRecurrence that could use the new overloads too. (Doesn't have to be done in this PR.)

Yeah, I'll do this in next PR

https://github.com/llvm/llvm-project/pull/189779