Searchable key config

[BramVerb]

Is your feature request related to a problem? Please describe.
It can be a bit time consuming to select a key from the large selection of keys.

Describe the solution you'd like
When opening the key-config dialog, it should autoFocus a search field.
Upon typing in the search field matching groups and/or keys would show up.

Describe alternatives you've considered
Using CTRL-F, but that does not seem to do anything.

Additional context
I've implemented it and opened a PR: #176