regexp lint: detect patterns that can cause catastrophic backtracking

[quasilyte]

This implementation may be ported to NoVerify:

• https://github.com/superhuman/rxxr2
• https://www.cs.bham.ac.uk/~hxt/research/rxxr2/

It doesn't look simple to port though.

More info on the kinds of patterns we want to detect:

• https://www.regular-expressions.info/catastrophic.html
• https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS
• https://stackoverflow.com/questions/12841970/how-can-i-recognize-an-evil-regex