What this PR does / why we need it:

1. Adds Search RPCs to RegistryServer.proto
2. Adds RPC implementations in registry_server.py
3. Adds support for registry_server.py registry calls to sql.py
4. Adds search.py to create Python objects for related RPCs
5. Adds tests for search.py in test_search.py
6. Bug fix for created_timestamp_column issue when materializing that broke tests
7. Streamlined last_updated_timestamp logic for projects, keeping same database connection
8. Other various test fixes

Which issue(s) this PR fixes:

Misc