[Feature] Enable Setting BigQuery Dataset Descriptions

[mlaforet]

Is this your first time submitting a feature request?

• [X] I have read the expectations for open source contributors
• [X] I have searched the existing issues, and I could not find an existing issue for this feature
• [X] I am requesting a straightforward extension of existing dbt-bigquery functionality, rather than a Big Idea better suited to a discussion

Describe the feature

The persist_docs feature supports materializing descriptions for tables and columns. It would be great to add support for adding dataset descriptions.

Describe alternatives you've considered

No response

Who will this benefit?

Users that want to add descriptions to datasets

Are you interested in contributing this feature?

perhaps...

Anything else?

No response

[simbazzuk]

@mlaforet I'm interested in contributing to this request as my first contribution. Do you have any further information on this?