Keep map selection when searching

[obydog002]

Fix #3092

Now retains the selected option

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (e3608b2) 59.37% compared to head (3f05b23) 59.37%.

Additional details and impacted files

@@            Coverage Diff             @@
##             develop    #3132   +/-   ##
==========================================
  Coverage      59.37%   59.37%           
+ Complexity      4506     4505    -1     
==========================================
  Files            574      574           
  Lines          20535    20539    +4     
  Branches        1019     1019           
==========================================
+ Hits           12193    12196    +3     
+ Misses          7803     7802    -1     
- Partials         539      541    +2     

Files	Coverage Δ
...om/faforever/client/game/CreateGameController.java	71.67% <80.00%> (+1.08%)	⬆️

... and 2 files with indirect coverage changes

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[Sheikah45]

Instead of introducing a mutable variable that we have to manually remember to set and track, I think it would be better to use the biconsumer version of subscribe on the selectedItem property in initMapSelection. This provides the new and old selected values, then if the new value is null we can select the old value if it is contained by filtered maps.

Effectively moving that logic outside of the setSelectedMap function.

Which is better for the long term as well since most of those properties set in setSelected map will be changed to be bound to derived properties eventually.

[Sheikah45]

The old item null check is superfluous but that is fine