Make project number as configurable as project id

[mummoo]

Is your feature request related to a problem? Please describe.
project number for the buckets is hardcoded as "1234".

"projectNumber": "1234",

This is not a valid GCP project number. So, instead allow this to be configurable in the same as the project id.

Describe the solution you'd like
Make the project number configurable.

        storage_client = storage.Client.create_anonymous_client()
        storage_client.project_number = <value> 

Describe alternatives you've considered
None

Additional context
None

[oittaa]

Project number doesn't seem to be included in the bucket creation query. Is it passed along somewhere else?