Add emit_signal method (#611) #1614

Job	Run time
cargo check (aarch64-android)	18s
cargo check (msrv) (wasm32)	21s
cargo clippy (windows-latest)	2m 34s
cargo check (msrv) (windows-latest)	3m 15s
cargo check (msrv) (macos-latest)	27s
cargo clippy (macos-latest)	1m 29s
cargo clippy (wasm32)	1m 9s
cargo check (msrv) (ubuntu-latest)	38s
cargo doc	1m 20s
cargo clippy (ubuntu-latest)	1m 40s
formatting	30s
cargo test (wasm32)	20s
Prime LFS Cache	4s
typos	6s
cargo test (windows-latest)	2m 48s
cargo test (macos-latest)	1m 24s
cargo test (ubuntu-latest)	4m 5s
	22m 28s

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