feat(storage): add StringLoader to support loading gs:// URL strings directly via Glide

[demolaf]

Closes #1842 .

Changes

FirebaseImageLoader previously only accepted a StorageReference as the Glide model, meaning callers who stored image paths as gs:// strings (e.g. retrieved from Firestore) had to manually convert them before loading. StringLoader eliminates that conversion by intercepting any string starting with gs:// and delegating to the existing FirebaseStorageFetcher.

Usage

Register StringLoader.Factory alongside the existing loader in your AppGlideModule:

@GlideModule
public class MyAppGlideModule extends AppGlideModule {

    @Override
    public void registerComponents(Context context, Glide glide, Registry registry) {
        registry.append(StorageReference.class, InputStream.class,
                new FirebaseImageLoader.Factory());
        registry.append(String.class, InputStream.class,
                new FirebaseImageLoader.StringLoader.Factory());
    }
}

You can then pass a gs:// URL string directly to Glide:

GlideApp.with(context)
        .load("gs://my-bucket.appspot.com/images/photo.png")
        .into(imageView);

Preview

[gemini-code-assist]

Code Review

This pull request introduces support for loading images directly from a gs:// URL string in Glide, including documentation updates in the README and the implementation of StringLoader in FirebaseImageLoader.java. The reviewer suggested improving the flexibility and testability of StringLoader by allowing it to accept a custom FirebaseStorage instance, as well as catching IllegalStateException to handle initialization edge cases gracefully.

[just1and0]

LGTM. Nice work with this one!