Provide a convenience method to support reading of last message from stream

[tishun]

Feature Request

A new way to read from the last element of the stream was introduced to XREAD with redis/redis#7388

We might want to add a convenience method to the XReadArgs.StreamOffset class.

Is your feature request related to a problem? Please describe

The feature could still be used if the + sign is used as offset in the XReadArgs.StreamOffset constructor.

Having a dedicated method would make it easier for the consumers of the driver.

Describe the solution you'd like

Add a new public static method that creates a StreamOffset with the hardcoded offset sign.

Describe alternatives you've considered

None.

Teachability, Documentation, Adoption, Migration Strategy

Similar to how the existing .latest(K name) and .lastConsumed(K name) methods were used.