Add search bar for filtering keyboard shortcuts

[ryan-carpenter]

JabRef allows users to customize keyboard shortcuts but does not provide a convenient way of searching and filtering the default settings and custom assignments. This makes it hard to identify unused key combinations and choose new shortcuts that fit with the existing ones.

Other applications that allow custom keyboard shortcuts provide a search bar for searching/filtering the existing assignments. As a JabRef user, I expect to find a search bar for this in "Preferences > Keyboard shorcuts". The search bar should accept actions or shortcuts and filter the current settings accordingly.

A search bar could be added above the keyboard shortcuts, like some other applications and matching the precedent in JabRef under "Preferences > Journal abbreviations".

Suggested location for new search bar

Precedent already in Preferences > Journal abbreviations