Add a setting to allow usage of native file dialogs in the preferences

Closes #274 and implements #568, at long last! Some issues remain:
- The native save pxo dialog doesn't have an "Include blended images" option. This will be fixed once https://github.com/godotengine/godot/pull/83480 is merged.
- When a native file dialog closes, the interface still remains dimmed.
- In the export dialog, the "Browse" file dialog will also close the export dialog itself when it closes, when it's native.

Translations/Translations.pot

@@ -743,6 +743,10 @@ msgstr ""
 msgid "Dim interface on dialog popup"
 msgstr ""
 
+#. Found in the preferences, under the interface section. When this setting is enabled, the native file dialogs of the operating system are being used, instead of Pixelorama's custom ones.
+msgid "Use native file dialogs"
+msgstr ""
+
 msgid "Dark"
 msgstr ""
 
@@ -2305,6 +2309,10 @@ msgstr ""
 msgid "Quit confirmation"
 msgstr ""
 
+#. Found in the preferences, under the startup section. Path is a noun and it refers to the location in the device where FFMPEG is located at. FFMPEG is a software name and it should not be translated. See https://en.wikipedia.org/wiki/Path_(computing)
+msgid "FFMPEG path"
+msgstr ""
+
 msgid "Enable autosave"
 msgstr ""
 

src/Preferences/PreferencesDialog.gd

@@ -11,6 +11,7 @@ var preferences: Array[Preference] = [
 	Preference.new("shrink", "%ShrinkSlider", "value"),
 	Preference.new("font_size", "Interface/InterfaceOptions/FontSizeSlider", "value"),
 	Preference.new("dim_on_popup", "Interface/InterfaceOptions/DimCheckBox", "button_pressed"),
+	Preference.new("use_native_file_dialogs", "Interface/InterfaceOptions/NativeFileDialogs", "button_pressed"),
 	Preference.new("icon_color_from", "Interface/ButtonOptions/IconColorOptionButton", "selected"),
 	Preference.new("custom_icon_color", "Interface/ButtonOptions/IconColorButton", "color"),
 	Preference.new("left_tool_color", "Interface/ButtonOptions/LeftToolColorButton", "color"),

src/Preferences/PreferencesDialog.tscn

@@ -209,6 +209,18 @@ mouse_default_cursor_shape = 2
 button_pressed = true
 text = "On"
 
+[node name="NativeFileDialogsLabel" type="Label" parent="HSplitContainer/VBoxContainer/ScrollContainer/RightSide/Interface/InterfaceOptions"]
+layout_mode = 2
+size_flags_horizontal = 3
+text = "Use native file dialogs"
+
+[node name="NativeFileDialogs" type="CheckBox" parent="HSplitContainer/VBoxContainer/ScrollContainer/RightSide/Interface/InterfaceOptions"]
+layout_mode = 2
+size_flags_horizontal = 3
+mouse_default_cursor_shape = 2
+button_pressed = true
+text = "On"
+
 [node name="ThemesHeader" type="HBoxContainer" parent="HSplitContainer/VBoxContainer/ScrollContainer/RightSide/Interface"]
 layout_mode = 2
 theme_override_constants/separation = 0