[zk-sdk] Expose `ElGamalPubkey` and `ElGamalKeypair` as wasm #10819

Job	Run time
cargo-test-sbf (token/program)	7m 18s
check	3m 27s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	16m 35s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	9m 22s
cargo-test-sbf (token-upgrade/program)	7m 44s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	16m 43s
cargo-test-sbf (feature-proposal/program)	7m 50s
cargo-test-sbf (governance/addin-mock/program, governance/program)	11m 45s
test (single-pool/cli, single-pool/program)	17m 15s
cargo-test-sbf (memo/program)	9m 45s
test (token-upgrade/cli, token-upgrade/program)	13m 58s
cargo-test-sbf (name-service/program)	10m 1s
cargo-test-sbf (stake-pool/program)	13m 29s
cargo-test-sbf (single-pool/program)	12m 4s
	2h 37m 16s

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