[wip] chore: replace PrimitiveSignature with Signature #67

Job	Run time
feature-checks	47s
no-std	27s
wasm-wasi	32s
doctest	34s
cfg-check	17s
clippy	26s
fmt	13s
docs	22s
wasm-unknown	23s
test ubuntu-latest stable --no-default-features	26s
test ubuntu-latest stable	24s
test ubuntu-latest stable --all-features	38s
test ubuntu-latest nightly --no-default-features	31s
test ubuntu-latest nightly	19s
test ubuntu-latest nightly --all-features	35s
test ubuntu-latest 1.79 --no-default-features	21s
test ubuntu-latest 1.79	21s
test windows-latest stable --no-default-features	2m 35s
test windows-latest stable	1m 53s
test windows-latest stable --all-features	1m 21s
test windows-latest nightly --no-default-features	1m 17s
test windows-latest nightly	1m 17s
test windows-latest nightly --all-features	1m 12s
test windows-latest 1.79 --no-default-features	1m 2s
test windows-latest 1.79	1m 15s
	19m 28s

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