Refactor model registry routes and configuration

[lucferbux]

Follow up of: RHOAIENG-4346

Description

Implements the proxy changes for model registry. This is still a work in progress continued in the effort of implementing Itsio authenticated routes.

How Has This Been Tested?

1. Tap into a cluster in DEV mode
2. Check that you can fetch resources with model registry

Test Impact

Request review criteria:

Self checklist (all need to be checked):

• The developer has manually tested the changes and verified that the changes work
• Commits have been squashed into descriptive, self-contained units of work (e.g. 'WIP' and 'Implements feedback' style messages have been removed)
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has added tests or explained why testing cannot be added (unit or cypress tests for related changes)

If you have UI changes:

• Included any necessary screenshots or gifs if it was a UI change.
• Included tags to the UX team if it was a UI/UX change (find relevant UX in the SMEs section).

After the PR is posted & before it merges:

• The developer has tested their solution on a cluster by using the image produced by the PR to main

[christianvogt]

/lgtm
/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: christianvogt

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