[mlir][vector] Allow values outside of [0; dim-size] in create_mask

This commits explicitly states that negative values and values exceeding
vector dimensions are allowed in vector.create_mask (but not in
vector.constant_mask). These values are now truncated when
canonicalizing vector.create_mask to vector.constant_mask.

Reviewed By: aartbik

Differential Revision: https://reviews.llvm.org/D116069