This PR introduces a new **CIR simplify for `switch` cases**, which
folds multiple **cascading `Equal` cases** (that contain only a
`YieldOp`) into a single `CaseOp` of kind `AnyOf`.
This logic is based on the suggestion from this discussion:
https://github.com/llvm/llvm-project/pull/138003#discussion_r2070564458
This patch adds the cir-simplify pass for SelectOp and TernaryOp. It
also adds the SelectOp folder and adds the constant materializer for the
CIR dialect.
