Fix admin map chooser not using display names for menu

[nosoop]

From the SM Discord:

4:52 PM] HiGPS: Is there any plugin that helps with the workshop map names not working properly in TF2, they show ID's and not the map names in the admin menu , but works in the nominations menu

This copies the display name-related lines from the LoadMapList function in basevotes/votemap.sp to basecommands/map.sp. It's otherwise left as-is — I'd have no issues changing the styling / hoisting the variable declaration to make it more consistent if desired.

[TheByKotik]

i'm think is not good idea.
Maps can have same name but must have unique paths.

[nosoop]

That's already an issue with using display names in the votemap menu with PR #354.

Personally, I'm indifferent on disambiguation (how many server ops have maps that share the same exact display name?). Having a togglable option to use the result of FindMap instead of GetMapDisplayName might be a compromise worth looking into; @TheByKotik might want to file an issue on it to get a proper discussion going.