Something like GcsFileSystem::Make()

Reporter: Carlos O'Ryan / @coryan
Assignee: Carlos O'Ryan / @coryan

Related issues:

• [C++] Add filesystem / IO implementation for Google Cloud Storage (is a child of)
• [C++] Add public factory function for GCS filesystem (supercedes)

PRs and other links:

• GitHub Pull Request #12180

_{Note: This issue was originally created as ARROW-15084. Please see the migration documentation for further details.}