HvH roundstart AI announcments (#7675)

# About the pull request

adds framework for AIs to get both factions updated on start of round

# Explain why it's good for the game

steel does not have to write it manualy


# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog
:cl:
qol: HvH roundstart AI announcements
/:cl:

---------

Co-authored-by: vincibrv <[email protected]>
Co-authored-by: Blundir <[email protected]>

code/game/gamemodes/extended/cm_vs_upp.dm

@@ -14,3 +14,8 @@
 	for(var/area/area in GLOB.all_areas)
 		area.base_lighting_alpha = 150
 		area.update_base_lighting()
+
+/datum/game_mode/extended/faction_clash/cm_vs_upp/announce()
+	. = ..()
+	marine_announcement("An automated distress call has been received from the local colony.\n\nAlert! Sensors have detected a Union of Progressive People's warship in orbit of colony. Enemy Vessel has refused automated hails and is entering lower-planetary orbit. High likelihood enemy vessel is preparing to deploy dropships to local colony. Authorization to interdict and repel hostile force from allied territory has been granted. Automated thawing of cryostasis marine reserves in progress.", "ARES 3.2", 'sound/AI/commandreport.ogg', FACTION_MARINE)
+	marine_announcement("Alert! Sensors have detected encroaching USCM vessel on an intercept course with local colony.\n\nIntelligence suggests this is the [MAIN_SHIP_NAME]. Confidence is high that USCM force is acting counter to Union interests in this area. Authorization to deploy ground forces to disrupt foreign power attempt to encroach on Union interests has been granted. Emergency awakening of cryostasis troop reserves in progress.", "1VAN/3", 'sound/AI/commandreport.ogg', FACTION_UPP)