Community server search

[l-Luna]

Adds a searchbar to the community servers menu. If there is a search query, a server is only displayed if its displayed text contains the query on refresh (e.g. with the search button).

While there's a lot of small improvements that could be made on top (e.g. allowing searching with regex, excluding group/map/server names, highlighting matches...), I felt this is good enough for things like "all attack maps" or "just this server group" without requiring a lot of changes.

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