f8c5a68365
We currently lack test coverage for [SemaTemplateDeduction.cpp#L1619-L1620](https://github.com/llvm/llvm-project/blob/fe20a75/clang/lib/Sema/SemaTemplateDeduction.cpp#L1619-L1620), which handles the case where both the P type and the A type are reference types but A is more cv-qualified than P. This is deemed non-deduced unless both A and P are possibly cv-qualified forms of the template parameter T. This PR adds tests for that logic.