Update tblproperties on incremental runs

[benc-db]

Addresses #760 (doesn't fully resolve because 760 also discusses comment updates)

Description

Incremental tables have not been updating tblproperties on incremental runs. This PR adds support for add/replace tblproperties on incremental run. Delete was tested, but too risky/complicated, as Databricks sets some tblproperties for tables on its own.

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.

[benc-db]

Adding Eric, Yunbo to review since Jacky is out. I will comment the code so that you have some context.