Add regexp/sort-flags rule

[ota-meshi]

No description provided.

[ota-meshi]

Thank you for your review!
I removed the option.

[RunDevelopment]

@ota-meshi I have a question: Do we have to worry about non-standard flags? v8 recently added an l flag. A standard JS parser will refuse to parse regexes with non-standard flags but a parser like Babel might just accept them.

[ota-meshi]

@RunDevelopment Thank you for the question!
I don't think the rule needs to handle and check non-standard flags, but I want to avoid the rule crashing due to non-standard flags.

There is a test case to check it.
https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/tests/lib/rules-with-unknown-flag.ts

The typescript-eslint parser accepts any unknown flags.

[RunDevelopment]

Thank you for the answer.

I wonder if we should make a rule to disallow non-standard flags. Will such a rule be helpful?

[ota-meshi]

Sounds good! I think it helpful for TypeScript users!

[RunDevelopment]

Alright, I'll add it :)