[llvm] [LV] Add target-independent test for type-mismatch (PR #130295)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> In the commit message you say `The test suite of LoopVectorize suffers from a coverage hole when types mismatch`, but what types are you referring to and in what context? It's not obvious what code path/problem you're trying to test.

Thanks, I've clarified this in the message, and added two more tests.

https://github.com/llvm/llvm-project/pull/130295