[mlir][linalg][bufferize] Rewrite "write into non-writable memory" detection

The purpose of this revision is to make "write into non-writable memory" conflict detection easier to understand.

The main idea is that there is a conflict in the case of inplace bufferization if:

1. Someone writes to (an alias of) opOperand, opResult or the to-be-bufferized op writes itself.
2. And, opOperand or opResult aliases a non-writable buffer.

Differential Revision: https://reviews.llvm.org/D111379