Add `Ui::columns_const()` #12024

Job	Run time
android	1m 7s
Check wasm32 + wasm-bindgen	2m 55s
cargo-deny aarch64-apple-darwin	41s
cargo-deny aarch64-linux-android	38s
Format + check + test	7m 26s
cargo-deny i686-pc-windows-gnu	41s
cargo-deny i686-pc-windows-msvc	36s
Check Windows	2m 50s
cargo-deny i686-unknown-linux-gnu	36s
cargo-deny wasm32-unknown-unknown	37s
cargo-deny x86_64-apple-darwin	42s
cargo-deny x86_64-pc-windows-gnu	38s
cargo-deny x86_64-pc-windows-msvc	35s
cargo-deny x86_64-unknown-linux-gnu	40s
cargo-deny x86_64-unknown-linux-musl	40s
cargo-deny x86_64-unknown-redox	38s
	22m 0s

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