Use faster regexp.test over string.match for testing against regex

[Encephala]

Description

As was mentioned by @xhaggi in this code review, regexp.test is faster than string.match if the goal is to check if a string matches a regular expression. string.match is only necessary if the goal is to extract a substring.

Out of the six places in HTMX where string.match is used, four of them can be replaced by regexp.test.

Corresponding issue: None, suppose that's not necessary for this small change, but correct me if I'm wrong.

Testing

I ran the testing suite and everything came out green.

Checklist

• I have read the contribution guidelines
• I have targeted this PR against the correct branch (master for website changes, dev for
  source changes)
• This is either a bugfix, a documentation update, or a new feature that has been explicitly
  approved via an issue
• I ran the test suite locally (npm run test) and verified that it succeeded

[Telroshan]

To back up your proposal, just linking this SO thread where a user posted some performance measurements between those 2