Build two Python connectors using the first base image version

[alafanechere]

Change the connector build process in airbyte-ci to:

1. Read the connectorBaseImage metadata value
   If connectorBaseImage is set:
2. Import this base image in the build process
3. Build a connector using the base image

I suggest to try this out on two non critical but stable connectors: source-faker and source-openweather.
We'll release a new version for each of this connector and confirm the new build process is working if their tests are passing.