[CT-460] Add set_query_tag to the dbt macro namespace

[robscriva]

Describe the feature

set_query_tag can only be overridden in the root project. By adding it to the dbt macro namespace, we can then leverage the dispatch functionality and override it with custom query tags in dbt packages.

Describe alternatives you've considered

The only way to achieve this is to add to the dbt macro namespace.

Additional context

https://getdbt.slack.com/archives/C37J8BQEL/p1633519489312300?thread_ts=1633377998.228400&cid=C37J8BQEL

Who will this benefit?

All dbt-snowflake users who have a central dbt package and would like to leverage custom query tags to be generated and stored at runtime. For example:

{
    "invocation_id": "{{ invocation_id }}",
    "run_started_at": "{{ run_started_at }}",
    "dbt_version": "{{ dbt_version }}",
    "project_name": "{{ project_name }}",
    "model":
    {
        "owners": "{{ tojson(model.meta.owners|default([])) }}",
        "database": "{{ this.database }}",
        "schema": "{{ this.schema }}",
        "name": "{{ this.name }}",
        "identifier": "{{ this.identifier }}",
        "path": "{{ model.path}}",
        "unique_id": "{{ model.unique_id }}",
        "materialized": "{{ model.config.materialized }}"
    }
}

Are you interested in contributing this feature?

Yes. #132 is currently in draft pending this issue creation.

[jtcohen6]

@robscriva Sorry for the delay getting back to you on this one! Totally reasonable request. I'll take a look at the PR now.