Introduce API to safely initialize Packets #12937

Job	Run time
check	2m 22s
cargo-test-sbf (token/program)	5m 0s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	5m 4s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	5m 0s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	4m 58s
test (single-pool/cli, single-pool/program)	5m 0s
cargo-test-sbf (token-upgrade/program)	4m 58s
cargo-test-sbf (feature-proposal/program)	4m 59s
test (token-upgrade/cli, token-upgrade/program)	4m 58s
cargo-test-sbf (governance/addin-mock/program, governance/program)	4m 59s
cargo-test-sbf (memo/program)	4m 59s
cargo-test-sbf (name-service/program)	5m 0s
cargo-test-sbf (stake-pool/program)	5m 0s
cargo-test-sbf (single-pool/program)	5m 3s
	1h 7m 20s

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