Add support for external tables with qualified names #32782

Job	Run time
build with wasm-pack	2m 24s
cargo test (macos)	9m 54s
cargo check	7m 47s
Check cargo fmt	40s
cargo test (macos-aarch64)	9m 40s
Verify MSRV (Min Supported Rust Version)	6m 59s
Verify Vendored Code	54s
cargo test (win64)	52m 48s
cargo test (amd64)	10m 23s
cargo examples (amd64)	13m 16s
check Cargo.toml formatting	3m 26s
clippy	6m 5s
cargo test hash collisions (amd64)	14m 53s
cargo doc	3m 59s
cargo test doc (amd64)	15m 16s
cargo test datafusion-cli (amd64)	3m 44s
Run sqllogictest with Postgres runner	3m 41s
cargo test pyarrow (amd64)	2m 49s
verify benchmark results (amd64)	12m 17s
check configs.md is up-to-date	2m 52s
	3h 3m 47s

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