Add a way to get autoloads through the api (#1131)

* add autoloads to api

* A name Dilemma, There are 2 autoloads for ImportApi

* add docstring

src/Autoload/ExtensionsApi.gd

@@ -381,6 +381,10 @@ class PanelAPI:
 
 ## Gives access to theme related functions.
 class ThemeAPI:
+	## Returns the Themes autoload. Allows interacting with themes on a more deeper level.
+	func autoload() -> Themes:
+		return Themes
+
 	## Adds the [param theme] to [code]Edit -> Preferences -> Interface -> Themes[/code].
 	func add_theme(theme: Theme) -> void:
 		Themes.add_theme(theme)
@@ -438,6 +442,10 @@ class ToolAPI:
 	# gdlint: ignore=constant-name
 	const LayerTypes := Global.LayerTypes
 
+	## Returns the Tools autoload. Allows interacting with tools on a more deeper level.
+	func autoload() -> Tools:
+		return Tools
+
 	## Adds a tool to pixelorama with name [param tool_name] (without spaces),
 	## display name [param display_name], tool scene [param scene], layers that the tool works
 	## on [param layer_types] defined by [constant LayerTypes],
@@ -678,6 +686,11 @@ class ExportAPI:
 	# gdlint: ignore=constant-name
 	const ExportTab := Export.ExportTab
 
+	## Returns the Export autoload.
+	## Allows interacting with the export workflow on a more deeper level.
+	func autoload() -> Export:
+		return Export
+
 	## [param format_info] has keys: [code]extension[/code] and [code]description[/code]
 	## whose values are of type [String] e.g:[codeblock]
 	## format_info = {"extension": ".gif", "description": "GIF Image"}
@@ -730,6 +743,15 @@ class ExportAPI:
 
 ## Gives access to adding custom import options.
 class ImportAPI:
+	## Returns the OpenSave autoload. Contains code to handle file loading.
+	## It also contains code to handle project saving (.pxo)
+	func open_save_autoload() -> OpenSave:
+		return OpenSave
+
+	## Returns the Import autoload. Manages import of brushes and patterns.
+	func import_autoload() -> Import:
+		return Import
+
 	## [param import_scene] is a scene preload that will be instanced and added to "import options"
 	## section of pixelorama's import dialogs and will appear whenever [param import_name] is
 	## chosen from import menu.
@@ -757,6 +779,10 @@ class ImportAPI:
 
 ## Gives access to palette related stuff.
 class PaletteAPI:
+	## Returns the Palettes autoload. Allows interacting with palettes on a more deeper level.
+	func autoload() -> Palettes:
+		return Palettes
+
 	## Creates and adds a new [Palette] with name [param palette_name] containing [param data].
 	## [param data] is a [Dictionary] containing the palette information.
 	## An example of [code]data[/code] will be:[codeblock]