[mlir][bufferize] Disallow adding new bufferizable ops during bufferization

Ops that are created during the bufferization were not analyzed (when run with One-Shot Bufferize), and users should instead create memref ops directly.

Futhermore, this fixes an issue where an op was erased (and put on the `erasedOps` list), but subsequently a new tensor op was created at the same memory location. This op was then not bufferized. Disallowing the creation of new tensor ops simplifies the bufferization and fixes such issues.

Differential Revision: https://reviews.llvm.org/D125017