Rust

Add example of dataframe API aggregations #2

Job	Run time
build with wasm-pack	2m 14s
cargo test (macos)	9m 12s
cargo test (macos-aarch64)	10m 43s
cargo check	3m 31s
Verify Vendored Code	52s
cargo test (win64)	32m 17s
Check cargo fmt	43s
Verify MSRV (Min Supported Rust Version)	6m 27s
cargo test datafusion-cli (amd64)	3m 35s
cargo test (amd64)	9m 18s
cargo doc	3m 45s
cargo test doc (amd64)	12m 55s
cargo examples (amd64)	13m 37s
Run sqllogictest with Postgres runner	3m 17s
cargo test pyarrow (amd64)	2m 38s
verify benchmark results (amd64)	10m 18s
check Cargo.toml formatting	2m 56s
clippy	5m 10s
check configs.md is up-to-date	2m 33s
cargo test hash collisions (amd64)	10m 37s
	2h 26m 38s

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