This commit removes the IEnvelopeExecutor interface and its implementation, replacing it with ISQLExecutor. The CreateEnvelopeAsync method in Extension.cs now directly creates DynamicParameters. The CreateEnvelopeCommandHandler has been updated to utilize ISQLExecutor. Additionally, the EnvelopeExecutor class has been removed, and a new SQL command class, EnvelopeReceiverCreateReadSQL, has been added for managing envelope receiver SQL operations.
Added a new static class `Extension` in `Extension.cs` to encapsulate methods for creating parameters and asynchronous envelope creation. Removed previous implementations from `EnvelopeCreateReadSQL.cs` for better organization. Updated `using` directives in `CreateEnvelopeCommandHandler.cs` and `EnvelopeCreateReadSQL.cs` for consistency.
