refactor: remove `S` generic from `InMemoryNode` and `ForkStorage` #1340

Job	Run time
lint	56s
build (ubuntu-latest)	4m 0s
build (macos-latest)	4m 22s
spec-tests / spec	2m 30s
e2e-tests / e2e (ubuntu-latest)	1m 6s
e2e-tests-rust / spec (ubuntu-latest)	1m 29s
e2e-tests / e2e (macos-latest)	1m 10s
e2e-tests-rust / spec (macos-latest)	1m 35s
	17m 8s

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