feat(RuleSet): impl RuleSet for syscalls::Sysno

[sivizius]

With this PR, defining types is not necessary if single syscalls should explicitly enabled.

[boustrophedon]

Thanks for the PR! I think this is a great idea for ergonomics when you want to enable something ad-hoc.

Would you mind just adding a simple test demonstrating how it works in a new file in the tests/ directory? If you'd like you can also mention the feature in the user guide or I can add that later.

[sivizius]

[x] test added

[boustrophedon]

Thanks!