Base changeling objective(s) (#39562)

Co-authored-by: slarticodefast <161409025+slarticodefast@users.noreply.github.com>

Resources/Locale/en-US/changeling/changeling.ftl

@@ -1,9 +1,6 @@
 roles-antag-changeling-name = Changeling
 roles-antag-changeling-objective = A intelligent predator that assumes the identities of its victims.
 
-changeling-role-greeting = You are a Changeling, a highly intelligent predator. Your only goal is to escape the station alive via assuming the identities of the denizens of this station. You are hungry and will not make it long without sustenance... kill, consume, hide, survive.
-changeling-briefing = You are a changeling, your goal is to survive. Consume humanoids to gain biomass and utilize it to evade termination. You are able to utilize and assume the identities of those you consume to evade a grim fate.
-
 changeling-devour-attempt-failed-rotting = This corpse has only rotted biomass.
 changeling-devour-attempt-failed-protected = This victim's biomass is protected.
 

Resources/Locale/en-US/game-ticking/game-presets/preset-changeling.ftl

@@ -0,0 +1,13 @@
+changeling-role-greeting =
+    You are a Changeling, a highly intelligent predator.
+    Your primary goal is to escape the station alive via assuming the identities of the denizens of this station.
+    You are hungry and will not make it long without sustenance...
+    Kill, consume, hide, survive.
+
+changeling-briefing =
+    You are a changeling.
+    You are able to utilize and assume the identities of those you consume to evade a grim fate.
+
+objective-issuer-changeling = [color=#FA2A55]The Hivemind[/color]
+
+changeling-round-end-agent-name = changeling

Resources/Prototypes/GameRules/roundstart.yml

@@ -232,6 +232,8 @@
   - type: GameRule
     minPlayers: 25
   - type: AntagSelection
+    agentName: changeling-round-end-agent-name
+    selectionTime: IntraPlayerSpawn
     definitions:
     - prefRoles: [ Changeling ]
       max: 3
@@ -249,6 +251,9 @@
         - ActionRetractableItemArmBlade # Temporary addition, will inevitably be a purchasable in the bio-store
       mindRoles:
       - MindRoleChangeling
+  - type: AntagObjectives
+    objectives:
+    - ChangelingSurviveObjective
 
 - type: entity
   id: Revolutionary

Resources/Prototypes/Objectives/changeling.yml

@@ -0,0 +1,23 @@
+- type: entity
+  abstract: true
+  parent: BaseObjective
+  id: BaseChangelingObjective
+  components:
+  - type: Objective
+    issuer: objective-issuer-changeling
+    difficulty: 1
+  - type: RoleRequirement
+    roles:
+    - ChangelingRole
+
+- type: entity
+  parent: [BaseChangelingObjective, BaseSurviveObjective]
+  id: ChangelingSurviveObjective
+  name: Survive.
+  description: We must stay alive at all cost.
+  components:
+  - type: Objective
+    difficulty: 1
+    icon:
+      sprite: Mobs/Species/Human/organs.rsi
+      state: heart-on