tools/resolve_btfids: Add --fatal_warnings option

Currently warnings emitted by resolve_btfids are buried in the build log
and are slipping into mainline frequently.

Add an option to elevate warnings to hard errors so the CI bots can catch
any new warnings.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20241204-resolve_btfids-v3-1-e6a279a74cfd@weissschuh.net