[llvm] [TableGen] Use buildConstant to emit apply pattern immediates (PR #66077)

[Jay Foad via llvm-commits]

jayfoad wrote:

> This adds flexibility, e.g. it allows us to seamlessly handle vector cases, where a G_BUILD_VECTOR is needed to create a splat.

Do you have any follow ups that would take advantage of that?

https://github.com/llvm/llvm-project/pull/66077