Currently, only an internal factory for GCS filesystem testing is provided. We need to add a public factory function, e.g.:

static Result<std::shared_ptr<S3FileSystem>> GcsFileSystem::Make(
    const GcsOptions& options,
    const io::IOContext& = io::default_io_context());

Reporter: Antoine Pitrou / @pitrou

Related issues:

• [C++] Add factory function for GcsFileSystem (is superceded by)

_{Note: This issue was originally created as ARROW-15191. Please see the migration documentation for further details.}