selftests/bpf: add stack access precision test

selftests/bpf: add stack access precision test

Add a new selftests that validates precision tracking for stack access
instruction, using both r10-based and non-r10-based accesses. For
non-r10 ones we also make sure to have non-zero var_off to validate that
final stack offset is tracked properly in instruction history
information inside verifier.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>