Add regexp/strict rule

[ota-meshi]

Related to #91 (comment).

[RunDevelopment]

I think that we shouldn't solely rely on new RegExpValidator({ strict: true }) here. The problems with RegExpValidator are that the error messages aren't precise (we only know that something is wrong but we can't give the exact location) and that reports aren't fixable.

I think that we should have our own logic that produces fixable reports (mostly dealing with required/forbidden escapes). Only after that logic can't find any problems will we use RegExpValidator (to make sure we haven't missed anything).

Shall I make a PR targeting this branch?

[ota-meshi]

Shall I make a PR targeting this branch?

Yes, thank you