Implement `Div<f64>` and `Mul<f64>` for `Insets` #733

Job	Run time
cargo check (msrv) (wasm32)	21s
cargo clippy (windows-latest)	1m 15s
cargo check (msrv) (windows-latest)	58s
cargo clippy (macos-latest)	36s
cargo clippy (wasm32)	45s
cargo check (msrv) (macos-latest)	29s
cargo clippy (ubuntu-latest)	47s
cargo doc	25s
cargo check (msrv) (ubuntu-latest)	28s
formatting	27s
cargo test (windows-latest)	53s
cargo test (wasm32)	16s
cargo test (macos-latest)	24s
typos	3s
cargo test (ubuntu-latest)	24s
	8m 31s

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