Cells: Provision additional cells that share clusterwide database with `make create-dev CELL=2`

This allows the GCK to provision many cells from the same GCK context.

The approach is simple:

make create-dev CELL=1
make create-dev CELL=2

And then if you run make web it will make to share clusterwide database:

make web CELL=1
make web CELL=2

It is important to always specify CELL= for each command as the lack of this option will remove database configuration changes that enable many CELLs.

After doing that there will be two GitLabs running:

• http://localhost:3000/
• http://localhost:3001/

This will make the additional cells to connect back to database owned by Cell 1 to fetch clusterwide tables. The same will apply for Redis in the future: fetch sessions.

Based on:

• !237 (merged)