[clang] [Clang][Interp] Implement constexpr vector unary operators +, -, ~, ! (PR #105996)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr commented:

Are these the only unary operators supported on vectors or are more to come? Since all (except for `+`, which doesn't do anything) cases call `prepareResult()` and `createTemp()` unconditionally, it would probably be cleaner to reject the unhandled cases via `emitInvalid` first, then do the `prepareResult()` + `createTemp()`(which don't even need to be lambdas anymore), then handle the actual operation.

https://github.com/llvm/llvm-project/pull/105996