Improve type safety in stake state module #8747

Job	Run time
check	3m 3s
cargo-test-sbf (token/program)	9m 28s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	18m 19s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	15m 45s
test (single-pool/cli, single-pool/program)	18m 19s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	10m 10s
test (token-upgrade/cli, token-upgrade/program)	16m 52s
cargo-test-sbf (token-upgrade/program)	8m 46s
cargo-test-sbf (feature-proposal/program)	8m 27s
cargo-test-sbf (governance/addin-mock/program, governance/program)	13m 37s
cargo-test-sbf (memo/program)	7m 22s
cargo-test-sbf (name-service/program)	7m 15s
cargo-test-sbf (stake-pool/program)	13m 9s
cargo-test-sbf (single-pool/program)	9m 20s
	2h 39m 52s

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