kleaf: abi: Add rule to invoke stgdiff directly.

* This is so `*_abi_diff_stg` can be invoked.

* Cleanup of previous XML support will be done as
follow ups.

* This is not integrated to kernel_abi_dist yet.

Bug: 261722616
Change-Id: Ib27299efa2ae597d3bb225ea5624825e5c318780
Signed-off-by: Ulises Mendez Martinez <umendez@google.com>
5 files changed