veristat: add ability to set BPF_F_TEST_SANITY_STRICT flag with -r flag

Add a new flag -r (--test-sanity), similar to -t (--test-states), to add
extra BPF program flags when loading BPF programs.

This allows to use veristat to easily catch sanity violations in
production BPF programs.

reg_bounds tests are also enforcing BPF_F_TEST_SANITY_STRICT flag now.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231112010609.848406-13-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>