[X86][CodeGen] Add a dag pattern to fix #64323

After recent patch D30189, #64323's error message become a new one.
When DAGCombiner was optimizing `(vextract (scalar_to_vector val, 0) -> val`, it didn't
consider the possibility that the inserted value type has less bit than the dest type.
This patch fixes that.

Reviewed By: pengfei

Differential Revision: https://reviews.llvm.org/D158355