Add Required slot checking in lobby logic. Set up needed player slots as Required for missions

mods/cnc-classic/maps/gdi01/map.yaml

@@ -42,6 +42,7 @@ Players:
 		InitialCash: 20
 		Allies: GoodGuy
 		Enemies: BadGuy,Creeps
+		Required: True
 	PlayerReference@Neutral:
 		Name: Neutral
 		OwnsWorld: True

mods/cnc-classic/maps/nod01/map.yaml

@@ -45,6 +45,7 @@ Players:
 		LockSpawn: True
 		LockTeam: True
 		Enemies: GDI,Neutral
+		Required: True
 
 Actors:
 	Actor0: rock2

mods/ra/maps/Survival01/map.yaml

@@ -41,6 +41,7 @@ Players:
 		LockSpawn: True
 		LockTeam: True
 		Enemies: Soviets
+		Required: True
 	PlayerReference@Soviets:
 		Name: Soviets
 		Race: soviet

mods/ra/maps/allies-01/map.yaml

@@ -44,6 +44,7 @@ Players:
 		LockTeam: True
 		Allies: Creeps
 		Enemies: Soviets
+		Required: True
 	PlayerReference@Soviets:
 		Name: Soviets
 		Race: soviet

mods/ra/maps/allies-02/map.yaml

@@ -38,6 +38,7 @@ Players:
 		LockTeam: True
 		Allies: Allies2,Allies
 		Enemies: Soviets
+		Required: True
 	PlayerReference@Allies2:
 		Name: Allies2
 		Playable: True

mods/ra/maps/allies-03/map.yaml

@@ -40,6 +40,7 @@ Players:
 		LockTeam: True
 		Allies: Allies2,Allies
 		Enemies: Soviets
+		Required: True
 	PlayerReference@Allies2:
 		Name: Allies2
 		Playable: True

mods/ra/maps/allies-04/map.yaml

@@ -45,6 +45,7 @@ Players:
 		LockTeam: True
 		Allies: Allies2,Allies
 		Enemies: Soviets
+		Required: True
 	PlayerReference@Allies2:
 		Name: Allies2
 		Playable: True

mods/ra/maps/monster-tank-madness/map.yaml

@@ -32,6 +32,7 @@ Players:
 		LockSpawn: True
 		LockTeam: True
 		Enemies: BadGuy,USSR,Ukraine,Turkey
+		Required: True
 	PlayerReference@BadGuy:
 		Name: BadGuy
 		Race: soviet

mods/ra/maps/soviet-01-classic/map.yaml

@@ -50,6 +50,7 @@ Players:
 		LockSpawn: True
 		LockTeam: True
 		Enemies: GoodGuy,France,Germany,Turkey
+		Required: True
 	PlayerReference@Turkey:
 		Name: Turkey
 		Race: allies