[mlir][bufferize] Support alloc hoisting across function boundaries

This change integrates the BufferResultsToOutParamsPass into One-Shot Module Bufferization. This improves memory management (deallocation) when buffers are returned from a function.

Note: This currently only works with statically-sized tensors. The generated code is not very efficient yet and there are opportunities for improvment (fewer copies). By default, this new functionality is deactivated.

Differential Revision: https://reviews.llvm.org/D125376