Make sdp.Server.Service a type alias

[zyv]

In my project, I must construct service records by hand and hit the following typing error in the process:

device.sdp_service_records = {
    handle: rfcomm.make_service_sdp_records(handle, channel, core.UUID(uuid))
    for uuid, handle in _SDP_SERVICE_HANDLES.items()
}

classic.py:536: error: Value expression in dictionary comprehension has incompatible type
"list[ServiceAttribute]"; expected type "Service"  [misc]

sdp.Server.Service is a NewType over list[ServiceAttribute], and a NewType is satisfied only by an explicit constructor call. Device.sdp_service_records is unannotated for that reason: annotating it with the NewType in-place causes mypy errors:

apps/rfcomm_bridge.py:112: error: Dict entry 0 has incompatible type
"int": "list[ServiceAttribute]"; expected "int": "Service"

I suggest to fix it as follows as the alternative to keep the nominal type and change every producer to return Server.Service breaks every downstream user who assigns a list they built themselves:

Make Service a type alias and give Device.sdp_service_records the annotation the NewType ruled out: sdp_records() helpers are already annotated with dict[int, list[ServiceAttribute]] by hand.