Bigquery repeated data type

[Thrasi]

resolves #190

This is a:

• bug fix with no breaking changes

Description & motivation

Separate format_column macro into default__format_column and bigquery__format_column to handle BigQuery REPEATED fields.

Checklist

• This code is associated with an issue which has been triaged and accepted for development.
• I have verified that these changes work locally
• I have updated the README.md (if applicable)
• I have added tests & descriptions to my models (and macros if applicable)
• I have added an entry to CHANGELOG.md

[dbeatty10]

@Thrasi this looks good to me!

Once you flip this to "ready to review", then we can give final approval and then merge.

Heads-up: Tomorrow will be my last day in the office before I'll be one holiday for a few weeks. If we can get it merged tomorrow, then great. Otherwise, I can pick it back up again when I return.

[Thrasi]

I'm not sure how the process for updating the CHANGELOG.md but this was my attempt

[dbeatty10]

Thanks for your work on this @Thrasi !

[dbeatty10]

I'm not sure how the process for updating the CHANGELOG.md but this was my attempt

Contributors don't need to manually update the CHANGELOG anymore, so I just pulled it out.

We've got a couple issues opened to update the PR template and contributing guide to remove those pieces so it isn't confusing in the future: #238 and #237