Moves BQ transforms outside of recipe.py and imports from outside module

[norlandrhagen]

Since pangeo-forge/pangeo-forge-runner#92 isn't quite done, this provides a work around to move all the Big Query transforms and table creation outside of the feedstock into a mini helper repo.

#39

[jbusecke]

Hey @norlandrhagen thanks for tackling these. I am debating internally if it is better to have another repo or make cmip6-feedstock installable/publish it on pypi. Are you planning to reuse these things outside of the CMIP context?

[norlandrhagen]

Some of the utilities could be used for cataloging, but don't feel super strongly if you want to go with the cmip6-feedstock pypi route.

[jbusecke]

I think this will actually help with #63, so let's move ahead here. We can always refactor things as needed later.

[jbusecke]

Oh weird. The Google auth does not work...wondering if this is because the PR branch is from another org?

values via GitHub secrets, ensure the secret is being injected into the environment. By default, secrets are not passed to workflows triggered from forks, including Dependabot.

ummm not sure how to get around this...