Adds read/write/get_pod() fns to tiered storage #4794

Job	Run time
cargo-test-sbf (token/program)	8m 2s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	13m 39s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	9m 23s
test	0s
cargo-test-sbf (token-upgrade/program)	7m 59s
check	0s
cargo-test-sbf (feature-proposal/program)	8m 23s
cargo-test-sbf (governance/addin-mock/program, governance/program)	12m 45s
cargo-test-sbf (memo/program)	9m 15s
cargo-test-sbf (name-service/program)	7m 39s
cargo-test-sbf (stake-pool/program)	11m 29s
cargo-test-sbf (single-pool/program)	8m 42s
	1h 37m 16s

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