Move utils/connection.py and exceptions/connection.py back to dbt-core

[MichelleArk]

          That said, dbt_common.utils.connection is not actually used in dbt/adapters or dbt-core so it'd be worth considering just defining it in dbt-core entirely.

Originally posted by @MichelleArk in #13 (comment)

[github-actions]

This issue has been marked as Stale because it has been open for 180 days with no activity. If you would like the issue to remain open, please comment on the issue or else it will be closed in 7 days.

[github-actions]

Although we are closing this issue as stale, it's not gone forever. Issues can be reopened if there is renewed community interest. Just add a comment to notify the maintainers.