Should unnecessary_raw_strings be enforced in RegExps?

[jamesderlin]

Describe the issue
I typically am in the habit of using raw strings with RegExps. IMO this is a good habit to have, even if using raw strings for a particular pattern isn't strictly necessary. Using a raw string allows me to not have to think. Should using raw strings unnecessarily when constructing a RegExp really be discouraged?

In the meantime, I'll probably just be disabling unnecessary_raw_strings entirely.

To Reproduce

var decimalRegExp = RegExp(r'\d+');
var hexRegExp = RegExp(r'(0x)?[0-9a-fA-F]+'); // unnecessary_raw_strings

Expected behavior
Perhaps relax the unnecessary_raw_strings lint if the string is used for a RegExp?

Bonus points if it also could recognize and ignore cases like:

const hexPattern = r'(0x)?[0-9a-fA-F]+';
var hexRegExp = RegExp(hexPattern);

although I'm far less concerned about that case.