refs #17413.
There are several commonly excluded directories in the lint tests. Rather than having these subtrees be copied in each of these test files, they can be pulled from a shared list so that any future changes to these exclusions can be isolated to one location rather than spread out among many files.
This first commit is a proof of concept demonstrating how this can be applied. I saw that we currently have a list of ignored words in a text file used for the spelling lint test, so I followed that general idea and moved the list of ignored subtrees into a text file as well. This can be read and parsed into whatever format we want. The extended-lint-cppcheck.sh and lint-includes.sh tests use a regex with just these directories, but some of the examples in the linked issue have additional unique exclusions so the solution needs to be able to support that.
I wanted to create an early WIP pull request with a proof of concept to present the idea for discussion. There are several other areas that this list of subtrees can be used, outlined in the ref'd issue.