Feature/protocol 22

[cuongph87]

What's Changed

• Added SubmitTransactionAsync function.
• Updated outdated reference links.
• Updated some Soroban unit tests.

Added support for Protocol 22

• Latest XDR changes.
• TxHash - hex-encoded transaction hash string - added to GetTransactionResponse and GetTransactionsResponse via TransactionInfo.
• Added CreateContractV2HostFunction.

Breaking changes

• Type of TransactionInfo.CreatedAt field (an indirect part of GetTransactionResponse and GetTransactionsResponse) changed from long to string.
• Amount and NumAccounts fields removed from AssetResponse.
• Cost field removed from SimulateTransactionResponse.
• PagingToken removed from GetEventsResponse.EventInfo and replaced with GetEventsResponse.Cursor.
• An extra parameter arguments added to CreateContractOperation.FromAsset static factory method to support CreateContractV2HostFunction.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.