Allow passing payload for domain add

[hardiksondagar]

Is your feature request related to a problem? Please describe.
While adding a domain, only the name is allowed to pass. MailerSend's other language library as allowed to pass parameters in addition to the name such as custom_tracking_subdomain etc.

Describe the solution you'd like
Allow all four parameters mentioned here while adding a domain.

Describe alternatives you've considered
One alternate I have considered is adding a domain and then updating those settings with the individual calls, but that will result in 4 calls to achieve this.

[igorhrcek]

Implemented, thank you for the report.