ot::Ncp::NcpBase::EncodeSrpClientServices() method

Adds a service to be registered with server. After a successful call to this function, `otSrpClientCallback` will be called to report the status of the service addition/registration with SRP server. The `otSrpClientService` instance being pointed to by @p aService MUST persist and remain unchanged after returning from this function (with `OT_ERROR_NONE`). OpenThread will save the pointer to the service instance. The `otSrpClientService` instance is not longer tracked by OpenThread and can be reclaimed only when - It is removed explicitly by a call to `otSrpClientRemoveService()` or removed along with other services by a call to `otSrpClientRemoveHostAndServices() and only after the `otSrpClientCallback` is called indicating the service was removed. Or, - A call to `otSrpClientClearHostAndServices()` which removes the host and all related services immediately.

Requests a service to be unregistered with server. After a successful call to this function, `otSrpClientCallback` will be called to report the status of remove request with SRP server. The `otSrpClientService` instance being pointed to by @p aService MUST persist and remain unchanged after returning from this function (with `OT_ERROR_NONE`). OpenThread will keep the service instance during the remove process. Only after the `otSrpClientCallback` is called indicating the service instance is removed from SRP client service list and can be be freed/reused.

Clears a service, immediately removing it from the client service list. Unlike `otSrpClientRemoveService()` which sends an update message to the server to remove the service, this function clears the service from the client's service list without any interaction with the server. On a successful call to this function, the `otSrpClientCallback` will NOT be called and the @p aService entry can be reclaimed and re-used by the caller immediately. Can be used along with a subsequent call to `otSrpClientAddService()` (potentially reusing the same @p aService entry with the same service and instance names) to update some of the parameters in an existing service.