POC: save calculated data for github repo stats in GCP BigQuery

[Max-Levitskiy]

Implementation, which should use this functionality: https://github.com/Web-tree/imprint/blob/master/backend/github/src/service/repo.service.ts

The BigQuery has a free tier limit high enough for our starting goals.

We should save in the BigQuery table imprint data for users.

Tables:

Cache for org stats:
Fields: user name(Github), week (timestamp), organisation, repo, commits amount, add, modified and delete lines.

Cache for repository stats
Fields: owner, is an organisation, repo name, branch name, week, commits amount, add, modified and delete lines, summary for the parameters for the week.

Imprint sources
Fields: union id, user-id, imprint.