This changes the initial connection negotiation to have the
ei_connection_setup as the pre-existing object id 0. Once the client has
sent all the data to set up the connection, the EIS implementation
replies with a new object ID that is the ei_connection protocol object,
i.e. the main object.
This allows for version negotiation of our main protocol object.
Directly copied from wayland. Note that while the wayland protocol
specifies the data is the last event serial in our case here it's just
0 since we don't have any event serials (yet).
The sync request is currently triggered after connection, merely to
ensure it works, it's not actually needed.
In the protocol this is a simple rename but in the implementation we can
now separate the protocol object out from the ei/ei-client context
itself by having the ei_connection objects.
