Allow for specifying sample time window in project configs

[QMalcolm]

Housekeeping

• I am a maintainer of dbt-core

Short description

In #11231 we introduced the ability to set a time window for sample mode as a CLI arg. This should also be able to be provided from the project configs so that it doesn't need to be provided as a CLI arg every time.

Acceptance criteria

• A sample time window can be specified in the project configs
• The CLI arg takes priority over the project config if both are provided

Suggested Tests

• A sample time window can be specified in the project configs
• The CLI arg takes priority over the project config if both are provided

Impact to Other Teams

N/A

Will backports be required?

No, it's a new feature

Context

N/A