[llvm] [TableGen] Support type aliases via new keyword deftype (PR #79570)

[Nicolai Hähnle via llvm-commits]

https://github.com/nhaehnle commented:

Thanks, I think this fits nicely with the language.

The change has a check whether a `deftype` conflicts with a pre-existing class definition, but it does not check whether a class definition conflicts with a pre-existing type alias. Please add that. Apart from that, this LGTM.

https://github.com/llvm/llvm-project/pull/79570