Implement flatten for MakeArray #18217

Job	Run time
Check cargo fmt	48s
Verify MSRV	10m 32s
cargo test (mac)	27m 44s
cargo check	9m 4s
Verify Vendored Code	1m 14s
cargo test (win64)	27m 48s
cargo examples (amd64)	7m 18s
cargo test hash collisions (amd64)	19m 32s
cargo doc	5m 51s
clippy	6m 26s
cargo test (amd64)	25m 16s
cargo test datafusion-cli (amd64)	4m 25s
cargo test doc (amd64)	17m 28s
Run sqllogictest with Postgres runner	4m 55s
cargo test pyarrow (amd64)	3m 13s
verify benchmark results (amd64)	36m 26s
check Cargo.toml formatting	2m 13s
check configs.md is up-to-date	4m 27s
	3h 34m 40s

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