Add Referrer feild in subscriber

[pratham-bhatnagar]

Fixes #1244

[github-actions]

• In the subscribe function, the verifyingContractAddress parameter is an optional parameter, but it should not be optional in this context. Update the type definition in SubscribeOptionsType to make it required if it is needed for the logic.
• In the subscribeV2 function, the origin parameter is optional but should be a required field for this context. Update the type definition in SubscribeOptionsV2Type to make it required.
• In the subscribeV2 function, the messageInformation object has a property data defined, but it is not required. Ensure that the data property is always present in the messageInformation object or update the logic accordingly.
• In the test suite, there is a commented-out test case Should subscribe to the channel via V2 with settings. This test case should be enabled or removed if no longer needed.

Apart from these points, the code logic and structure seem fine.

Code Review Comments:

• All looks good.