L10, L11: Fix robot not being moved by move_local_x (#1229)

Previously, when running move_local_x, the robot didn't seem to move.
This happened because the node that was actually receiving the message
move_local_x was the scene root, which was the parent of both Robot and
Camera0D. This means that the Robot was actually moving but the
Camera2D was moving as well.

The fix is basically the same change in both lessons:
- Moved the scene script from the robot to the scene root (in L11 also
removed the Built-in script from the scene root).
- Made the Camera2D top level inside _ready() so its position will be
independent from the scene root, so when the root is moved by
move_local_x, the Robot moves away while the Camera2D stays in place.

Fixes #1228

Author: JuanFdS

course/lesson-10-the-game-loop/rotating-and-moving/RotateAndMoveSprite.gd

@@ -1,8 +1,10 @@
 extends Node2D
 
+onready var camera_2d := $Camera2D
 
 func _ready() -> void:
 	set_process(false)
+	camera_2d.set_as_toplevel(true)
 
 
 # EXPORT move_and_rotate

course/lesson-10-the-game-loop/rotating-and-moving/RotateAndMoveSprite.tscn

@@ -4,9 +4,9 @@
 [ext_resource path="res://course/common/Robot.tscn" type="PackedScene" id=2]
 
 [node name="RotateAndMoveSprite" type="Node2D"]
+script = ExtResource( 1 )
 
 [node name="Robot" parent="." instance=ExtResource( 2 )]
-script = ExtResource( 1 )
 
 [node name="Camera2D" type="Camera2D" parent="."]
 current = true

course/lesson-11-time-delta/rotating-and-moving-delta/RotatingMovingSpriteDelta.gd

@@ -1,8 +1,10 @@
 extends Node2D
 
+onready var camera_2d := $Camera2D
 
 func _ready() -> void:
 	set_process(false)
+	camera_2d.set_as_toplevel(true)
 
 
 # EXPORT move_and_rotate

course/lesson-11-time-delta/rotating-and-moving-delta/RotatingMovingSpriteDelta.tscn

@@ -1,23 +1,12 @@
-[gd_scene load_steps=4 format=2]
+[gd_scene load_steps=3 format=2]
 
 [ext_resource path="res://course/lesson-11-time-delta/rotating-and-moving-delta/RotatingMovingSpriteDelta.gd" type="Script" id=1]
 [ext_resource path="res://course/common/Robot.tscn" type="PackedScene" id=2]
 
-[sub_resource type="GDScript" id=1]
-script/source = "extends Node2D
-
-
-onready var _scene := $Robot
-
-func reset():
-	_scene.reset()
-"
-
 [node name="RotatingMovingSpriteDelta" type="Node2D"]
-script = SubResource( 1 )
+script = ExtResource( 1 )
 
 [node name="Robot" parent="." instance=ExtResource( 2 )]
-script = ExtResource( 1 )
 
 [node name="Camera2D" type="Camera2D" parent="."]
 current = true