[TF2] Add new MvM keyvalues, fix support not giving money

[HyperionCoding]

Adds two new keyvalues to Mvm: SpawnUntilAllSpawned and SpawnUntilAllDead. These allow support robots to spawn only while another subwave is active. This behaviour is otherwise impossible to achieve.

Also fixes bug where populator marked Support does not give its money at the end of the wave if it never started spawning, eg. had state PENDING or PRE_SPAWN_DELAY.