Add Meta Prebuilt APK Install Tool

[devloglogan]

This PR builds on top of the work in #15

For ease of review I've kept commits separate, including a commit that runs .clang-format on all of the c++ files. Some of the updates / additions to Fredia's work:

• Updated the export process to check the new vendor plugin project settings.
• generatePrebuiltApks now serves as a standalone task, it won't be run when building the plugin.
  • To run generatePrebuiltApks it needs to be pointed to a godot directory with -Pgodot_dir=path/to/godot
  • This will create a meta-export-template.zip file in the project root, with the idea that we'll host them here in releases of the Godot Meta Toolkit.
  • I've removed the godot submodule since it's now longer needed.
• Added an editor tool that downloads/installs the export the prebuilt apks.
  • Download url is created form a new base url editor setting (default pointing towards this github repo) and I've added a GODOT_META_TOOLKIT_VERSION define in a new file version.h.

[dsnopek]

Thanks! This looks great :-)

I've only got a couple notes/questions on the code

Otherwise, the only other important thing to note here is that this will only work with Godot 4.5 (because we need EditorExportPlugin::_update_android_prebuilt_manifest()) and so merging this will make the plugin 4.5+

We'll want to consider when we want to do this, or if we want to make two builds (one that's 4.3+ and another that's 4.5+), or maybe two major versions?

If we go with two builds, we could come up with a way to have a single codebase, where we wrap the new code with #if GODOT_VERSION_PATCH >= 5, which will check if the provided extension_api.json is for Godot 4.5 or later. Then we just need CI to make two builds with two different extension_api.jsons

[dsnopek]

This should probably check that the directory exists as well. And since this needs to be done in a bunch of places, it probably makes sense to move this check into a function

[devloglogan]

Added checking that it exists / is a directory, and extracted it out to a verifyGodotDir() function.

[dsnopek]

The Godot version should be included in the filename, so that we match the editor version with the template version. So, something like:

Suggested change

	String download_url = (String)editor_settings->get_setting("xr/meta_toolkit/base_download_url") + GODOT_META_TOOLKIT_VERSION + "/meta-export-template.zip";
	const GDExtensionGodotVersion2 &godot_version = godot::internal::godot_version;
	String filename = vformat("meta-export-template-v%d.%d.%d-%s", godot_version.major, godot_version.minor, godot_version.patch, godot_version.status);
	String download_url = (String)editor_settings->get_setting("xr/meta_toolkit/base_download_url") + GODOT_META_TOOLKIT_VERSION + "/" + filename;

We may need to update godot-cpp to get GDExtensionGodotVersion2 which has the .status field

[devloglogan]

I've updated the godot-cpp version and applied this change!