[mlir][linalg][bufferize] Eliminate InitTensorOps of InsertSliceOp sources

An InitTensorOp is replaced with an ExtractSliceOp on the InsertSliceOp's destination. This optimization is applied after analysis and only to InsertSliceOps that were decided to bufferize inplace. Another analysis on the new ExtractSliceOp is needed after the rewrite.

Differential Revision: https://reviews.llvm.org/D111955