Add screenshot functionality and new level scene to game manager

scripts/screenshot.gd

@@ -0,0 +1,8 @@
+extends Node
+
+func _process(_delta: float) -> void:
+	if OS.is_debug_build() and Input.is_action_just_pressed("screenshot"):
+		var img  := get_viewport().get_texture().get_image()
+		var id   := OS.get_unique_id() + "_" + Time.get_datetime_string_from_system()
+		var path := "user://screenshot_" + str(id) + ".png"
+		img.save_png(path)