Adjust type + field names for ComputedExportedServices
The existing type and field names in `ComputedExportedServices` are confusing to work with.
For example, the mechanics of looping through services and their consumers wind up being:
```go
// The field name here doesn't reflect what is actually at each index of the list
for _, service := range exportedServices.Consumers {
for _, consumer := range service.Consumers {
// The prefix matching the type here causes stutter when reading and
// isn't consistent with naming conventions for tenancy in pbresource
tenancy := consumer.ConsumerTenancy
}
}
```