Executes a Verto RPC method targeting a specific participant.
Constructs call context (node_id, call_id, member_id) and sends the RPC request.
Target member ID string, or a MemberTarget object.
Verto method name (e.g. 'call.mute', 'call.member.remove').
Parameters for the RPC method.
Promise<T>
The RPC response.
If the RPC call returns an error.
execute — lower-level raw JSON-RPC send.