Game crash / too high memory usage on start if too many maps

[cclecle]

Motivation

If the game is loaded with a lot of custom maps (100+ in my tests), then the memory usage explode to 2, 3 GB or more and might crash.
The next release will introduce server map list accessible to client, so map list will probably get bigger, especially on dedicated server

Proposed solution

Do not let map Packages openned in memory after app start.
Open the package for discovery/checking/lint on start, then close the package, and finally reoppenn the package only when needed.

Side effects

Maybe a very small delay on map start because the package will have to be reopenned, should be unsignificant.

Alternatives

Accept having 3, 4 or more GB of ram per instance to allows game to run .

[PunkPun]

closed by #21408