achievementUnlocked
This signal is emitted when calling the com.jacobibanez.plugin.android.godotplaygameservices.GodotAndroidPlugin.incrementAchievement or com.jacobibanez.plugin.android.godotplaygameservices.GodotAndroidPlugin.unlockAchievement methods.
Return
true if the achievement is unlocked. false otherwise. Also returns the id of the achievement.