[mlir] Introduce CloneOp and adapt test cases in BufferDeallocation.

Add a new clone operation to the memref dialect. This operation implicitly
copies data from a source buffer to a new buffer. In contrast to the linalg.copy
operation, this operation does not accept a target buffer as an argument.
Instead, this operation performs a conceptual allocation which does not need to
be performed manually.

Furthermore, this operation resolves the dependency from the linalg-dialect
in the BufferDeallocation pass. In addition, we also extended the canonicalization
patterns to fold clone operations. The copy removal pass has been removed.

Differential Revision: https://reviews.llvm.org/D99172