Beginning to reorg the functional tests

[benc-db]

Description

To make it easier to determine which functional tests we're missing, I'm adopting the organizational strategy of the adapter folder in core. From migrating these tests, I found that I had added a duplicate test in the last PR because of the difficulty of tracking which tests we have vs which we're missing.

Couple of other notes

• Added alias tests we were missing
• test_basic.py has been exploded into a lot of really simple files, primarily to keep alignment with core, but also because sometimes we have a situation like with doc generation where we need a large override, and I don't like python files that feel like a grab bag of unrelated things.
• I've started moving Databricks to the front of the test class names. I prefer to have the stuff we want to ignore (TestDatabricks) in one place, rather than sandwiching them around the part of the test name that has meaning.

Checklist

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

[benc-db]

For discussion: Do we need Databricks in the name at all? In cases where dbt doesn't have a base for us to inherit its necessary, but I think when they do that, it's more an accident due to time crunch than an intentional choice.

[susodapop]

LGTM. I checked these out locally and explored in the VSCode test explorer and they are much easier to walk through 👍

Should we include "Databricks" in the test cases?
I think no. If we need to override a test case in dbt-core or dbt-spark we can add "Override" to the test case to make it more clear what's happening and why.