Fix font code for Godot 4 in Finite State Machine (#1027)

This clears out some errors that happen on every load of this demo in Godot 4 onward.
It also makes the fonts actually work, as they did not before.

We probably don't strictly **need** these font settings for a demo, but they were here before.

I don't think `SourceCodePro-Black.ttf` was ever used, based on looking at history. So I removed it.

Both `.tres` files are gone too, as those are not used in Godot 4.

I have updated everything that used `SourceCodePro-Bold.ttf` to the new setup.

2d/finite_state_machine/Demo.tscn

@@ -1,6 +1,7 @@
-[gd_scene load_steps=8 format=3 uid="uid://dmn8nkpogiwsf"]
+[gd_scene load_steps=9 format=3 uid="uid://dmn8nkpogiwsf"]
 
 [ext_resource type="PackedScene" uid="uid://bpdyvy2681m3i" path="res://player/Player.tscn" id="1"]
+[ext_resource type="FontFile" uid="uid://b5bspum6ffekd" path="res://fonts/SourceCodePro-Bold.ttf" id="2_r1c5f"]
 [ext_resource type="PackedScene" uid="uid://cvi13chv8g4hj" path="res://debug/StatesStackDiplayer.tscn" id="3"]
 [ext_resource type="PackedScene" uid="uid://bq6rrfy53rfvo" path="res://debug/ControlsPanel.tscn" id="4"]
 
@@ -43,6 +44,9 @@ libraries = {
 "": SubResource("AnimationLibrary_qbwwp")
 }
 
+[node name="StateNameDisplayer" parent="Player" index="5"]
+theme_override_fonts/font = ExtResource("2_r1c5f")
+
 [node name="Explanations" type="RichTextLabel" parent="."]
 anchors_preset = 15
 anchor_right = 1.0

2d/finite_state_machine/debug/StatesStackDiplayer.tscn

@@ -1,6 +1,7 @@
-[gd_scene load_steps=2 format=3 uid="uid://cvi13chv8g4hj"]
+[gd_scene load_steps=3 format=3 uid="uid://cvi13chv8g4hj"]
 
 [ext_resource type="Script" path="res://debug/states_stack_displayer.gd" id="1"]
+[ext_resource type="FontFile" uid="uid://b5bspum6ffekd" path="res://fonts/SourceCodePro-Bold.ttf" id="2_58if7"]
 
 [node name="StatesStackDiplayer" type="Panel"]
 offset_right = 210.0
@@ -17,6 +18,7 @@ grow_vertical = 2
 
 [node name="Title" type="Label" parent="VBoxContainer"]
 layout_mode = 2
+theme_override_fonts/font = ExtResource("2_58if7")
 text = "StateStack"
 uppercase = true
 
@@ -26,12 +28,14 @@ layout_mode = 2
 [node name="Numbers" type="Label" parent="VBoxContainer/HBoxContainer"]
 unique_name_in_owner = true
 layout_mode = 2
+theme_override_fonts/font = ExtResource("2_58if7")
 text = "1.
 2."
 horizontal_alignment = 2
 
 [node name="States" type="Label" parent="VBoxContainer/HBoxContainer"]
 unique_name_in_owner = true
 layout_mode = 2
+theme_override_fonts/font = ExtResource("2_58if7")
 text = "Jump
 Test"