chore(client): vendor GUT 9.7.1 + headless test harness

client/addons/gut/gui/update_required.gd

@@ -0,0 +1,30 @@
+@tool
+extends AcceptDialog
+
+var should_continue = false
+var _check_for_update_ctrl = null
+
+signal closed
+
+func _ready():
+	add_cancel_button("Cancel Loading GUT")
+
+
+func _on_confirmed() -> void:
+	should_continue = true
+	closed.emit.call_deferred()
+
+
+func _on_canceled() -> void:
+	should_continue = false
+	closed.emit.call_deferred()
+
+
+func _on_close_requested() -> void:
+	should_continue = false
+	closed.emit.call_deferred()
+
+
+func set_check_for_update_control(ctrl):
+	_check_for_update_ctrl = ctrl
+	add_child(ctrl)