Obtain and configure GCS bucket for diagnostic reports

No matter which approach we will use with uploading diagnostic reports, the most convenient place to store them would be the dedicated GCS bucket.

For example, in my PoC testing uploads from Puma, I used uploads bucket, but it would be more convenient to have a separate bucket for diagnostic reports only.
It would simplify the cleanup and also the access control (it is desired that engineers could browse the bucket freely).