[llvm] [IR][NFC] Introduce Constant::containsMatchingVectorElement and corresponding matcher m_ContainsMatchingVectorElement (PR #200502)

[Sean Clarke via llvm-commits]

xarkenz wrote:

The replacement of the `Constant::contains{Undef,Poison,UndefOrPoison}Element` functions seemed to be problematic, so I've reverted those changes for this PR. `Constant::containsConstantExpression` and `maskContainsAllOneOrUndef` should be OK to replace, though.

https://github.com/llvm/llvm-project/pull/200502