Rebels can be filtered by skill

[mhulet]

Is your feature request related to a problem? Please describe.
A coordinator should be able to filter rebels by skill (eg. Public speaking). This is not possible currently.

Describe the solution you'd like
Using the search box on top of the rebels table.

Describe alternatives you've considered
Exporting all rebels and filtering using the spreadsheet software.

Additional context
Would work fine by using skills 3-letter codes, searching for skill:PUB. We need a hidden column in the table that includes this specific string.