feat(match): matches by PR title and body

[kalvarez2]

Description:
Enhances the glob matchers to support matching a text on PR title or body.
The change is backwards compatible, no need to change the existing configurations. Any and All continue to work.
The matchers now support prefix "title:" and "body:"
Simple example:

label1:

• "body:#potato"

=>Would add the label "label1" if the body contains the string #potato

The existing all and any continue to work:
isText:

• all: ['*.txt', 'body:#isOnlyText']

=> Would set the label isText if both all the files have extension txt, and the body contains "#isOnlyText"

The change is backwards compatible, but documentation changes with examples are also included, comments / enhancements are very welcome.

Related issue:
#55

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[jmeridth]

@kalvarez2 any chance we can pick this back up? Would love this feature to be available in this action. @MaksimZhukov is this something this action is interested in?

[mofosyne]

Would like to follow up on this as an alternative to using https://github.com/Bhacaz/label-regex

[mwarkentin]

This would be useful for us as well, using branch names can catch some of the PRs I'd like to label, but I suspect we'll miss a bunch which might have a keyword we could use in the PR description or title.

My use case is to label incident-related PRs.

[ok-coder1]

Superseded for PR title by #866.