Upfront ask to dispatch new macros

[dataders]

This is a:

• bug fix PR with no breaking changes — please ensure the base branch is master
• new functionality — please ensure the base branch is the latest dev/ branch
• a breaking change — please ensure the base branch is the latest dev/ branch

Description & motivation

To get tsql-utils current with 0.6.5 (dbt-msft/tsql-utils#49), I had to disable many new tests that went with new macros. When undispatched macros are added to dbt-utils, it requires two PRs to get the new macro working with TSQL:

1. a PR to dbt-utils to allow the new macro to be dispatched
2. a PR to tsql-utils adding the shim logic for the new macro.

My proposal would be to strive for all new proposed macros to have dispatch logic before merging. The rationale being:

• IIRC, releases can't be used for submodules, yet
• submodules are how the shim packages (tsql-utils, spark-utils, presto-utils) import dbt-utils.

This makes it hard to selectively add new functionality to the shim packages without taking all commits to master

Checklist

• I have verified that these changes work locally on the following warehouses (Note: it's okay if you do not have access to all warehouses, this helps us understand what has been covered)
  • BigQuery
  • Postgres
  • Redshift
  • Snowflake
• 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

[clrcrl]

Generally in favor of calling this out, but have some feedback on where we put this

[jtcohen6]

Thanks @swanderz, totally on board with this!