newFakeProxier was inlining the details of NewEndpointsChangeTracker
so it could override trackerStartTime, but it would be better and more
future-proof to just call NewEndpointsChangeTracker normally and then
edit that one field.
(Also remove an unused FakeProxier field.)
EndpointSliceCache was using the name "endpointInfo" to refer to two
different data types (most egregiously in addEndpoints(), which had a
variable named `endpoint` of type `*endpointInfo` and a variable named
`endpointInfo` of type `Endpoint`).
Continue using "endpointInfo" in places that refer to proxy.Endpoint /
BaseEndpointInfo, since that's consistent with other code, but rename
the local "cache of the Endpoints field of an EndpointSlice" type from
"endpointInfo" to "endpointData". Likewise, rename endpointSliceInfo
to endpointSliceData, for consistency.
Move the ServicePort/BaseServicePortInfo types to serviceport.go.
Move the Endpoint/BaseEndpointInfo types to endpoint.go.
To avoid confusion with the new filenames, rename service.go to
servicechangetracker.go and endpoints.go to endpointschangetracker.go.
(No code changes; this just moves some code from types.go and
services.go to serviceport.go, and some code from types.go and
endpoints.go to endpoint.go.)
