match-3 grid generation

make game scene modular
global debug mode

scenes/game/gameplays/clickomania_gameplay.tscn

@@ -0,0 +1,21 @@
+[gd_scene load_steps=2 format=3 uid="uid://cl7g8v0eh3mam"]
+
+[ext_resource type="Script" path="res://scenes/game/gameplays/clickomania_gameplay.gd" id="1_script"]
+
+[node name="Clickomania" type="Node2D"]
+script = ExtResource("1_script")
+
+[node name="Label" type="Label" parent="."]
+anchors_preset = 8
+anchor_left = 0.5
+anchor_top = 0.5
+anchor_right = 0.5
+anchor_bottom = 0.5
+offset_left = -100.0
+offset_top = -12.0
+offset_right = 100.0
+offset_bottom = 12.0
+grow_horizontal = 2
+grow_vertical = 2
+text = "Clickomania Gameplay (Demo)"
+horizontal_alignment = 1