Destination Bigquery: more details about GCS/BigQuery required permissions

[alafanechere]

1. The exact permissions needed for GCS (for BigQuery staging) were a bit confusing. I think there's an open issue about the multipart upload being required already?
2. Same for the permissions for BigQuery. This could be made more obvious in the docs

Created from Slack: https://airbytehq.slack.com/archives/C019WJFR1JT/p1640892635138800

[andriikorotkov]

@alafanechere, about 1 item in this task - Charles added part to the doc with link to a BigQuery documentation and with list of needed GCS permissions (these changes merged on 07.01.22). As for me, this is a good description of this item. I've added a similar list of permits needed to work with BigQuery, and added a link to the documentation with information about which permits apply to each role. We also already had links on how to create a service account and step-by-step instructions on how to set up an account. These changes will be added with this pull request - #11238. Please, if you have comments and suggestions regarding the documentation, write them in this issue and I will try to process and add them to the documentation.