Add note array and view.

rhythm_game/note/note.gd

@@ -0,0 +1,18 @@
+class_name Note extends Object
+
+enum TYPE {
+	TAP = 0,
+	HOLD_START = 1,
+	HOLD_END = 2
+}
+
+var hit_beat: float
+
+var type: TYPE
+
+var lane: int
+
+func _init(p_hit_beat: float = -99.0, p_lane: int = 0, p_type: TYPE = TYPE.TAP) -> void:
+	hit_beat = p_hit_beat
+	lane = p_lane
+	type = p_type