Add annotation for session affinity path

[zrdaley]

What this PR does / why we need it:
This PR adds an annotation, session-cookie-path, that is used to set the path on the affinity cookie when regular expressions are used.

Which issue this PR fixes: fixes #3362

[ElvinEfendi]

@zrdaley you also need to adjust internal/ingress/types_equals.go

[zrdaley]

@ElvinEfendi I changed Expect(len(errs)).Should(BeNumerically("==", 0)) to Expect(errs).Should(BeEmpty()) but the former is still used in a LOT of the e2e tests.

[aledbf]

@ElvinEfendi I changed Expect(len(errs)).Should(BeNumerically("==", 0)) to Expect(errs).Should(BeEmpty()) but the former is still used in a LOT of the e2e tests.

@zrdaley I fixed that here a51136b

[ElvinEfendi]

/lgtm
/approve

[k8s-ci-robot]

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