Rust

Add `opacity` and `multiply_opacity` functions to `Ui` and `Painter` #11454

Job	Run time
Format + check + test	5m 23s
android	21s
Check wasm32 + wasm-bindgen	2m 15s
cargo-deny aarch64-apple-darwin	43s
Check Windows	2m 26s
cargo-deny aarch64-linux-android	39s
cargo-deny i686-pc-windows-gnu	40s
cargo-deny i686-pc-windows-msvc	40s
cargo-deny i686-unknown-linux-gnu	43s
cargo-deny wasm32-unknown-unknown	38s
cargo-deny x86_64-apple-darwin	42s
cargo-deny x86_64-pc-windows-gnu	39s
cargo-deny x86_64-pc-windows-msvc	41s
cargo-deny x86_64-unknown-linux-gnu	39s
cargo-deny x86_64-unknown-linux-musl	40s
cargo-deny x86_64-unknown-redox	41s
	18m 30s

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