Add VPCEndpointService Ref support to VPCEndpoint

[a-mcloughlin]

Issue #, if available: N/A

Description of changes:
Adding a VPCEndpointService and to the VPCEndpoint crd,
referencing ec2 VPCEndpointService by ServiceName

Structure:

apiVersion: ec2.services.k8s.aws/v1alpha1
kind: VPCEndpoint
metadata:
  name: test
spec:
  serviceRef:
    from:
      name: test
...

Tested locally, everything works as intended, and existing functionality is not impacted.

Thanks for taking the time to review!
I appreciate any feedback on this PR

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[ack-prow]

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This pull-request has been approved by: a-mcloughlin
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[ack-prow]

Hi @a-mcloughlin. Thanks for your PR.

I'm waiting for a aws-controllers-k8s member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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