Fix initial frequencies for support aircraft.

Vaicom (a mod that adds voice control for the communications menus)
isn't able to follow the waypoint frequency change that normally sets
the radio channel for the AWACS/tanker flights. Set the group's
frequency correctly to start so it works.

gen/airsupportgen.py

@@ -89,6 +89,7 @@ class AirSupportConflictGenerator:
                 speed=574,
                 tacanchannel=str(tacan),
             )
+            tanker_group.set_frequency(freq.mhz)
 
             callsign = callsign_for_support_unit(tanker_group)
             tacan_callsign = {
@@ -131,6 +132,8 @@ class AirSupportConflictGenerator:
                     frequency=freq.mhz,
                     start_type=StartType.Warm,
                 )
+                awacs_flight.set_frequency(freq.mhz)
+
                 awacs_flight.points[0].tasks.append(SetInvisibleCommand(True))
                 awacs_flight.points[0].tasks.append(SetImmortalCommand(True))