Remove sd-id128

[kennylevinsen]

Removing sd-id128 from the library requires removing the following from the sd-bus API:

int sd_bus_set_server(sd_bus *bus, int b, sd_id128_t bus_id);
int sd_bus_get_bus_id(sd_bus *bus, sd_id128_t *id);
int sd_bus_get_name_machine_id(sd_bus *bus, const char *name, sd_id128_t *machine);

Not entirely sure what purpose this serves.