SQLAlchemy 2: implement and refactor schema reflection methods (#249)

Signed-off-by: Jesse Whitehouse <[email protected]>

Author: Jesse

CONTRIBUTING.md

@@ -158,6 +158,10 @@ python -m pytest test_suite.py --dburi \
 Some of these of these tests fail currently. We're working on getting relevant tests passing and others skipped. The tests that we've already reviewed and verified
 are decorated with a pytest marker called `reviewed`. To only run these tests and check for regressions, you can add `-m reviewed` to the invocation command above.
 
+These tests require two schemas exist in your catalog:
+- An empty schema which can have an arbitrary name. It is configured in the SQLAlchemy --dburi
+- An empty schema named `test_schema`
+
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