Add info to wiki explaining how to probe local emulated GCS

[U8NWXD]

When working on code that interacts with Google Cloud Storage (GCS), it's often useful to be able to explore the files that exist in our local emulated GCS. You can do this as follows:

1. Run the local dev server
2. Open a shell to the oppia-dev-server container: make shell.oppia-dev-server
3. Start a Python session python
4. Depending on what Oppia tools you want to use, you may need to run import scripts.start to get Python to look in the correct folders for imports.
5. import models: from core.platform import models
6. Set up storage_services: storage_services = models.Registry.import_storage_services()

Now you can explore GCS as follows:

# The `abc` is the GCS bucket name, which you can put anything for.
>>> storage_services.listdir('abc', 'exploration_suggestions/25/assets')
[EmulatorBlob(name=exploration_suggestions/25/assets/image/img_20241203_121203_tn09emjdm7_height_472_width_314_micro.svg, content_type=image/svg+xml), EmulatorBlob(name=exploration_suggestions/25/assets/image/img_20241203_121203_tn09emjdm7_height_472_width_314_compressed.svg, content_type=image/svg+xml), EmulatorBlob(name=exploration_suggestions/25/assets/image/img_20241203_121203_tn09emjdm7_height_472_width_314.svg, content_type=image/svg+xml)]

You can also mutate files in GCS. See the available functions here: https://github.com/oppia/oppia/blob/develop/core/platform/storage/dev_mode_storage_services.py