feat: Cache SQL columns and schemas #4187

Job	Run time
Test on 3.7 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 4s
External Tests	1m 2s
Test on 3.8 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 5s
Test on 3.9 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 4s
Test on 3.10 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 5s
Test on 3.11 (tests) / ubuntu-latest / SQLAlchemy: 2.*	1m 6s
Test on 3.7 (tests) / macos-latest / SQLAlchemy: 2.*	49s
Test on 3.8 (tests) / macos-latest / SQLAlchemy: 2.*	50s
Test on 3.9 (tests) / macos-latest / SQLAlchemy: 2.*	49s
Test on 3.10 (tests) / macos-latest / SQLAlchemy: 2.*	1m 5s
Test on 3.11 (tests) / macos-latest / SQLAlchemy: 2.*	48s
Test on 3.7 (tests) / windows-latest / SQLAlchemy: 2.*	49s
Test on 3.8 (tests) / windows-latest / SQLAlchemy: 2.*	53s
Test on 3.9 (tests) / windows-latest / SQLAlchemy: 2.*	50s
Test on 3.10 (tests) / windows-latest / SQLAlchemy: 2.*	53s
Test on 3.11 (tests) / windows-latest / SQLAlchemy: 2.*	52s
Test on 3.11 (tests) / ubuntu-latest / SQLAlchemy: 1.*	1m 5s
Test on 3.10 (doctest) / ubuntu-latest / SQLAlchemy: 2.*	39s
Test on 3.8 (mypy) / ubuntu-latest / SQLAlchemy: 2.*	53s
Coverage	1s
	17m 42s

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