Rust

Move mod-level docstring to `DragAndDrop` #9011

Job	Run time
Format + check + test	5m 40s
android	27s
Check Windows	1m 34s
Check wasm32 + wasm-bindgen	2m 40s
cargo-deny aarch64-apple-darwin	44s
cargo-deny aarch64-linux-android	41s
cargo-deny i686-pc-windows-gnu	41s
cargo-deny i686-pc-windows-msvc	42s
cargo-deny i686-unknown-linux-gnu	39s
cargo-deny wasm32-unknown-unknown	39s
cargo-deny x86_64-apple-darwin	39s
cargo-deny x86_64-pc-windows-gnu	38s
cargo-deny x86_64-pc-windows-msvc	41s
cargo-deny x86_64-unknown-linux-gnu	41s
cargo-deny x86_64-unknown-linux-musl	49s
cargo-deny x86_64-unknown-redox	39s
	18m 34s

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