feat(gcs): support filename prefix filtering in listContents

[mouize]

Summary

This PR adds support for arbitrary filename prefix filtering to the GoogleCloudStorageAdapter::listContents() method.

Currently, the adapter forces a trailing / on the prefix, which prevents listing objects by filename prefix.
Ex: my_folder/my_file_prefixes_

This PR removes the forced /, allowing both directory and filename prefix listing as supported by Google Cloud Storage natively.

Why
• GCS natively supports prefix filtering server-side.
• Current adapter prevents efficient listing of large buckets by filename prefix.
• This makes Flysystem closer to native GCS behavior.

Fixes #1879

[frankdejonge]

Hi, this would be a breaking change on the behavioural contract so will not be merged as it. What is possible, is to add a listContentsAsPrefix option (default to false) to allow people to opt-in to this behaviour.

[mouize]

Hi, this would be a breaking change on the behavioural contract so will not be merged as it. What is possible, is to add a listContentsAsPrefix option (default to false) to allow people to opt-in to this behaviour.

Right ! Thx for the review. Just pushed a new update