Airdrop functionality

[RickyLB]

Signed-off-by: Ricky Saechao ricky@launchbadge.com Description:

This PR incorporates functionality for Token Airdrops: TokenAirdropTransaction, TokenClaimAirdropTransaction, TokenCancelAirdropTransaction, PendingAirdropId, and PendingAirdropRecord

Related issue(s):

• https://github.com/hashgraph/hedera-sdk-swift/issues/347
• https://github.com/hashgraph/hedera-sdk-swift/issues/374
• https://github.com/hashgraph/hedera-sdk-swift/issues/373
• https://github.com/hashgraph/hedera-sdk-swift/issues/372
• https://github.com/hashgraph/hedera-sdk-swift/issues/371
• https://github.com/hashgraph/hedera-sdk-swift/issues/370
• https://github.com/hashgraph/hedera-sdk-swift/issues/376

Fixes #

Notes for reviewer:

Checklist

• [x] Documented (Code comments, README, etc.)
• [x] Tested (unit, integration, etc.)

[sonarcloud[bot]]

Quality Gate failed

Failed conditions
13.9% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud