Extract poll refresh pipeline from cursor

[benc-db]

Description

Extracting polling for DLT pipeline refresh so that it doesn't weirdly live on a cursor. Need to add new unit tests for client.

Checklist

• [x] I have run this code in development and it appears to resolve the stated issue
• [x] This PR includes tests, or tests are not required/relevant for this PR
• [x] I have updated the CHANGELOG.md and added information about my change to the "dbt-databricks next" section.