Allow filtering of rules in rules command

[natanrolnik]

I started implementing a filtering feature in the rules command yesterday. For example, showing only enabled, disabled, the ones that only show warnings, and more.

When looking into the code, I initially thought of adding options to RulesOptions. But as RulesCommand accepts only one Argument at the moment, I think it would make sense one of the choices:

A - Keep using RulesCommand for both; if a rule identifier is passed, it always wins over the other options; otherwise, it will list all rules (and filter if filter-enabled is passed).
B - Create a new command, RuleCommand (Singular, not plural), that prints only the rule that relates to the passed identifier. And keep RulesCommand only for displaying multiple rules, according to the filtering options.

Both choices have their pros/cons, and I personally prefer A. Do you see any better way of doing this? I'll be happy to open a PR in the next few days according to the suggestions here.

[natanrolnik]

Ok, I gave it a try in #1275 and chose option A. Please let me know your thoughts.

[marcelofabri]

Fixed in #1293 💯