Rust

Export expr_fn, restore tests #87

Job	Run time
build with wasm-pack	2m 25s
cargo check	3m 25s
Check cargo fmt	48s
cargo test (macos)	20m 3s
cargo test (macos-aarch64)	18m 24s
Verify MSRV (Min Supported Rust Version)	7m 8s
Verify Vendored Code	48s
cargo test (win64)	46m 13s
clippy	6m 7s
check configs.md is up-to-date	2m 31s
check Cargo.toml formatting	3m 10s
cargo test hash collisions (amd64)	10m 9s
cargo doc	4m 8s
cargo test (amd64)	10m 49s
cargo test datafusion-cli (amd64)	3m 39s
cargo test doc (amd64)	13m 34s
cargo examples (amd64)	11m 40s
Run sqllogictest with Postgres runner	3m 19s
cargo test pyarrow (amd64)	2m 57s
verify benchmark results (amd64)	10m 18s
	3h 1m 35s

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