Refactor gameplay menus into owned scenes

ui/menus/FormationMenu.tscn

@@ -0,0 +1,90 @@
+[gd_scene load_steps=4 format=3]
+
+[ext_resource type="Script" path="res://ui/IconButton.gd" id="10"]
+[ext_resource type="Script" path="res://ui/FormationEditor.gd" id="17"]
+[ext_resource type="Script" path="res://ui/menus/FormationMenu.gd" id="menu_script"]
+
+[node name="FormationMenu" type="Control" groups=["modal_menus"]]
+visible = false
+mouse_filter = 2
+anchor_right = 1.0
+anchor_bottom = 1.0
+script = ExtResource("menu_script")
+
+[node name="Backdrop" type="ColorRect" parent="."]
+mouse_filter = 2
+anchor_right = 1.0
+anchor_bottom = 1.0
+color = Color(0.03, 0.03, 0.08, 0.94)
+
+[node name="TitleLabel" type="Label" parent="."]
+mouse_filter = 2
+anchor_right = 1.0
+offset_left = 24
+offset_top = 70
+offset_right = -24
+offset_bottom = 220
+theme_override_font_sizes/font_size = 44
+autowrap_mode = 2
+text = "Fleet formation - drag to arrange"
+horizontal_alignment = 1
+
+[node name="Editor" type="Control" parent="."]
+mouse_filter = 2
+anchor_left = 0.5
+anchor_right = 0.5
+anchor_top = 0.5
+anchor_bottom = 0.5
+offset_left = -300
+offset_right = 300
+offset_top = -300
+offset_bottom = 300
+script = ExtResource("17")
+
+[node name="ResetButton" type="Control" parent="."]
+anchor_left = 0.5
+anchor_right = 0.5
+anchor_top = 1.0
+anchor_bottom = 1.0
+offset_left = -74
+offset_right = 74
+offset_top = -270
+offset_bottom = -122
+script = ExtResource("10")
+icon = 3
+
+[node name="ResetLabel" type="Label" parent="."]
+mouse_filter = 2
+anchor_left = 0.5
+anchor_right = 0.5
+anchor_top = 1.0
+anchor_bottom = 1.0
+offset_left = -180
+offset_right = 180
+offset_top = -114
+offset_bottom = -8
+theme_override_font_sizes/font_size = 60
+text = "Reset"
+horizontal_alignment = 1
+
+[node name="CloseButton" type="Control" parent="."]
+anchor_left = 1.0
+anchor_right = 1.0
+offset_left = -172
+offset_right = -24
+offset_top = 24
+offset_bottom = 172
+script = ExtResource("10")
+icon = 1
+
+[node name="FadeOverlay" type="CanvasLayer" parent="."]
+layer = 10
+
+[node name="FadeRect" type="ColorRect" parent="FadeOverlay"]
+mouse_filter = 2
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+color = Color(0, 0, 0, 0)