feat(find): add JACK find_package module

[bruxisma]

This PR brings several important fixes in addition to the new feature:

1. Duplicate target and component names are now correctly removed.
2. We now know we'll need a breaking change fix for find::library, as the HEADER argument fails in all cases where the directory location and package share the same name.
3. Some internal documentation markdown was fixed.

It is unfortunate that the JACK2 interface, library, and packages are so confusing between Windows and Linux. Very little effort has been done to make it clear that the jack2 API is hidden behind packages like jackd, which have nothing to do with libjack-dev.

Thankfully, it seems we're "one of the first" in this space, as there are effectively no FindJACK2.cmake files on github, and the ones that are provide a simplistic API that will not eventually support:

• Static Library Preferences
• Finding the jackd Daemon itself (for launching via tests, I assume)
• Automatic target importing