Add port name to service struct used in minikube service

[arnaudjardine]

Fixes: #3351

[k8s-ci-robot]

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[minikube-bot]

Can one of the admins verify this patch?

[tstromberg]

Nicely done! If you could please add a test for this in service_test.go, I would be very happy to see this get merged. Otherwise, we're bound to accidentally break this in a future release. :(

[arnaudjardine]

Hi @tstromberg, I've added a test for that ;)

[tstromberg]

Thank you!

@minikube-bot OK to test