[feature]: enable / disable all buttons to quickly add patterns to playlist

[caleyg]

A feature that would be useful is enabling and disabling all UI buttons to quickly add all the available patterns in the UI instead of only being able to click them each one by one.

I have been tinkering with different approaches while keeping the original implementation as much as possible. If I am successful, I'll push up a PR with this implemented.

[caleyg]

included in this PR https://github.com/simap/Firestorm/pull/44