feat(isvc): made name and url optional - added support to svc url annotation

[Al-Pragliola]

Description

This PR aims to add backwards compatibility to existing inferenceservices that are missing the new labels/annotations, so the following changes have been made:

• made the name label and URL annotation optional, the reconciler will try to connect to a model registry service in the namespace specified by the label or the default (if missing), if there's more than one MR service it will stop and fail.
• The reconciler will try to get the URL from the service's annotation if it's specified and it's present on the service, if it's missing it will build the URL using the name/namespace/rest-api port.

How Has This Been Tested?

make test

Merge criteria:

• All the commits have been signed-off (To pass the DCO check)

• The commits have meaningful messages; the author will squash them after approval or in case of manual merges will ask to merge with squash.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work.
• Code changes follow the kubeflow contribution guidelines.

[google-oss-prow]

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