I would like to create a login method with a custom icon, but I am so far unable to figure out how I should do that.
To add an icon to a login mehtod, you create a file `resources/sprite/login_1x/XYZ.png` and add the following to the associated `src/auth/PhabricatorAuthProviderXXX.php`:
```lang=php
protected function getLoginIcon() {
return 'XYZ';
}
```
Afterwards you have to call two scripts to create the sprite map:
```
./scripts/celerity/generate_sprites.php
./bin/celerity map
```
However, I provide my login method as a library in a different repository/directory (to be enabled via `conf/local/local.json: load-libraries`). How am I supposed to make the icon available in this case?