selftests/bpf: add trusted global subprog arg tests

Add a bunch of test cases validating behavior of __arg_trusted and its
combination with __arg_nullable tag. We also validate CO-RE flavor
support by kernel for __arg_trusted args.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240130000648.2144827-5-andrii@kernel.org


Signed-off-by: Alexei Starovoitov <ast@kernel.org>