lazy load agate

[dwreeves]

TLDR:

• Lazy loading agate saves 3.5% load-up time on all operations that don't require agate. (aka many of them)
• dbt labs is on board with this, it's already been implemented in dbt-core and it's likely to be implemented in dbt-adapters: lazy load agate and add TYPE_CHECKING dbt-labs/dbt-adapters#126

[dwreeves]

@jwills Looks like test failure has nothing to do with the code change?

[jwills]

Yeah sorry, it's a creds issue with MotherDuck, nothing to do with the code. Duly merging-- thanks again!