[mlir][linalg][bufferize] Move more helper functions/structs to interface

Move helper functions for traversing reverse use-def chains. These are useful for implementing custom optimizations (e.g., custom InitTensorOp eliminations).

Also move over the AllocationCallbacks struct. This is in preparation for decoupling ComprehensiveBufferize from various dialects.

Differential Revision: https://reviews.llvm.org/D113386