refactor(signer): small refactor in signer utils #4983

Job	Run time
doctest	3m 7s
wasm-unknown	2m 45s
clippy	1m 40s
check no_std	1m 4s
feature-checks	8m 7s
test ubuntu-latest stable --no-default-features	2m 30s
docs	1m 7s
test ubuntu-latest stable	2m 42s
test ubuntu-latest stable --all-features	3m 10s
fmt	14s
wasm-wasi	3m 36s
test ubuntu-latest nightly --no-default-features	1m 30s
test ubuntu-latest nightly	1m 29s
test ubuntu-latest nightly --all-features	2m 23s
test ubuntu-latest 1.79 --no-default-features	1m 38s
test ubuntu-latest 1.79	1m 54s
test windows-latest stable --no-default-features	5m 54s
test windows-latest stable	5m 36s
test windows-latest stable --all-features	6m 14s
test windows-latest nightly --no-default-features	3m 37s
test windows-latest nightly	3m 34s
test windows-latest nightly --all-features	4m 49s
test windows-latest 1.79 --no-default-features	3m 31s
test windows-latest 1.79	3m 8s
ci success	2s
	1h 15m 21s

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