[mlir][bufferization][NFC] Put inplacability conflict resolution in op interface

The TensorCopyInsertion pass resolves out-of-place bufferization decisions by inserting explicit `bufferization.alloc_tensor` ops. This change moves that functionality into a new BufferizableOpInterface method, so that it can be overridden by op implementations. Some op bufferizations must insert additional `alloc_tensor` ops to make sure that certain aliasing invariants are not violated (e.g., scf::ForOp). This will be addressed in a subsequent change.

Differential Revision: https://reviews.llvm.org/D126817