Add new rule for detecting some unescaped dots

[scripthunter7]

If an unescaped dot (.) is found in a regex pattern, and it can be reasonably determined that the dot is still part of a valid domain or is followed by a valid TLD, a warning should be displayed, suggesting that the dot should be escaped.

For example, the following rules:

/example.ru\/uploads\/banner\d+.png/
/example.(com|org)/

Should be rewritten as:

/example\.ru\/uploads\/banner\d+.png/
/example\.(com|org)/

This is because an unescaped dot (.) in a regex pattern represents any character, while an escaped dot (\.) explicitly represents a literal dot (.).

Can be autofixed.