[mlir][linalg][bufferize] Rewrite conflict detection

For each memory read, follow SSA use-def chains to find the op that produces the data being read (i.e., the most recent write). A memory write to an alias is a conflict if it takes places after the "most recent write" but before the read.

This CL introduces two main changes:
* There is a concise definition of a conflict. Given a piece of IR with InPlaceSpec annotations and a computes alias set, it is easy to compute whether this program has a conflict. No need to consider multiple cases such as "read of operand after in-place write" etc.
* No need to check for clobbering.

Differential Revision: https://reviews.llvm.org/D111287