Support unparsing plans after applying `optimize_projections` rule #34611

Job	Run time
build with wasm-pack	2m 43s
cargo check	4m 53s
Check cargo fmt	39s
cargo test (macos)	5m 8s
cargo test (macos-aarch64)	5m 8s
Verify MSRV (Min Supported Rust Version)	4m 53s
Verify Vendored Code	50s
cargo test (win64)	4m 59s
cargo test datafusion-cli (amd64)	1s
cargo test (amd64)	1s
cargo examples (amd64)	1s
cargo test doc (amd64)	1s
clippy	1s
cargo test hash collisions (amd64)	1s
cargo doc	1s
Run sqllogictest with Postgres runner	1s
cargo test pyarrow (amd64)	1s
verify benchmark results (amd64)	1s
check Cargo.toml formatting	1s
check configs.md and ***_functions.md is up-to-date	1s
	29m 25s

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