Added Support for api_endpoint config

[OTooleMichael]

resolves dbt-labs/dbt-bigquery#358
Rework of dbt-labs/dbt-bigquery#1017

Ala @jtcohen6
Allows api_endpoint to be set in BigQuery connection profile. This expands out optionally allowing to api_endpoint to be set. This is supported Biqquery way of overriding the http endpoint, similar to Snowflake. Issue 358 references this. Users may try running with a BQ emulator or proxy, but dbt Labs makes no guarantees of officially supported emulators or proxies.

Problem

Bigquery Connection provides a native way to set the api_endpoint (similar to how the host can be set for most other connectors) - This allows the end user to utilise this GoogleBQ option as they see fit.

Solution

The Code simply acknowledges this BigQuery settings and accepts to pick it up from DBT credentials, and pass it onwards to BQ when present.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change in the dbt-bigquery package. For details on how to document a change, see the Contributing Guide.

[MartinSahlen]

Hey @jtcohen6, appreciate if you can get this in at your earliest convenience - thanks!

[colin-rogers-dbt]

@OTooleMichael applied some code formatting here and now should be good to go, thanks for all the work to get this over the line!

[OTooleMichael]

@OTooleMichael applied some code formatting here and now should be good to go, thanks for all the work to get this over the line!

Thanks so much. Will be nice to have this close :)

[jessebrowning]

Hi all. Any chance this is merging soon?