Remove aggregate functions dependency on frontend #255

Job	Run time
cargo test (macos)	9m 46s
cargo test (win64)	57m 4s
cargo check	10m 51s
Check cargo fmt	43s
build with wasm-pack	2m 38s
cargo test (macos-aarch64)	12m 39s
Verify MSRV (Min Supported Rust Version)	7m 5s
Verify Vendored Code	54s
cargo test (amd64)	10m 25s
cargo test datafusion-cli (amd64)	3m 59s
cargo examples (amd64)	13m 36s
check Cargo.toml formatting	2m 56s
clippy	6m 1s
check configs.md is up-to-date	2m 47s
cargo test hash collisions (amd64)	14m 47s
cargo doc	3m 53s
cargo test doc (amd64)	15m 56s
Run sqllogictest with Postgres runner	3m 35s
cargo test pyarrow (amd64)	3m 20s
verify benchmark results (amd64)	12m 44s
	3h 15m 39s

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