Don't crash if modelregistries namespace is not present in the DSC

[mturley]

Followup to #3239
Needed for https://issues.redhat.com/browse/RHOAIENG-12311

Description

See slack thread here. The above PR creates a situation where if model registry is not enabled on a cluster, the dashboard will crash on server start. This PR is an immediate fix for the crash, and I'll follow up with a second PR to switch us to using a ResourceWatcher so we make sure the namespace value is current in case it is not available yet when the dashboard starts.

This PR also fixes the same type in the frontend to make sure we are always being defensive when we try to read this value.

How Has This Been Tested?

Tested on https://console-openshift-console.apps.ods-qe-psi-01.osp.rh-ods.com/ which is old enough that its DSC has no modelregistry spec or status. Running the backend locally on main, verified that it crashes when using this cluster's API. Running the same way on this branch there is no crash.

Test Impact

N/A, no tests in the backend.

Request review criteria:

Self checklist (all need to be checked):

• The developer has manually tested the changes and verified that the changes work
• 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.

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

[mturley]

/hold
We're also not strict enough with the same type in the frontend, will fix momentarily

[mturley]

/unhold

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 85.04%. Comparing base (3af499a) to head (4abe660).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...nd/src/pages/modelRegistrySettings/CreateModal.tsx	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3248      +/-   ##
==========================================
- Coverage   85.06%   85.04%   -0.02%     
==========================================
  Files        1293     1293              
  Lines       28846    28846              
  Branches     7759     7759              
==========================================
- Hits        24538    24533       -5     
- Misses       4308     4313       +5     

Files with missing lines	Coverage Δ
...lRegistry/context/ModelRegistrySelectorContext.tsx	100.00% <100.00%> (ø)
frontend/src/k8sTypes.ts	100.00% <ø> (ø)
...delRegistrySettings/ModelRegistriesPermissions.tsx	96.77% <100.00%> (ø)
...elRegistrySettings/useModelRegistryRoleBindings.ts	66.66% <100.00%> (ø)
...nd/src/pages/modelRegistrySettings/CreateModal.tsx	68.67% <0.00%> (ø)

... and 6 files with indirect coverage changes

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[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andrewballantyne, gitdallas

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