Refactor envtest mocks & client logic for catalog-source ConfigMap handling

[ederign]

Description

This PR is a starting point for refactoring based on my conversations with @ppadti. I left a considerable number of TODOs that will be addressed by @ppadti in a FUP PR.

This change aligns our handling of the model-catalog-default-sources and model-catalog-sources ConfigMaps and aligns our test/mock environment (envtest).

In this PR:

• Reverted modelCatalogSettingsRepository mock creation to align with your k8s mock strategy
• Implemented GetAllCatalogSourceConfigs for the default catalog
• Setup env test for model-catalog-source-config

Next steps:

FUP PR from @ppadti to write the full implementation

How Has This Been Tested?

run the application in mock mode make dev-start

try these curl commands:

get all source configs:

curl -X GET "http://localhost:4000/api/v1/settings/model_catalog/source_configs?namespace=kubeflow" -H "kubeflow-userid: [email protected]"

add a catalog source config:

curl -X POST "http://localhost:4000/api/v1/settings/model_catalog/source_configs?namespace=kubeflow" -H "kubeflow-userid: [email protected]" -H "Content-Type: application/json" -d '{"data":{"id":"test-catalog","name":"Test Catalog","type":"yaml"}}' 

get a catalog source config:

curl -s "http://localhost:4000/api/v1/settings/model_catalog/source_configs/test-catalog?namespace=kubeflow" -H "kubeflow-userid: [email protected]" 

Update a catalog source config:

curl -X PATCH "http://localhost:4000/api/v1/settings/model_catalog/source_configs/test-catalog?namespace=kubeflow" -H "kubeflow-userid: [email protected]" -H "Content-Type: application/json" -d '{"data":{"id":"test-catalog","name":"Updated Catalog","type":"yaml"}}'

Delete a catalog source config:

curl -X DELETE "http://localhost:4000/api/v1/settings/model_catalog/source_configs/test-catalog?namespace=kubeflow" -H "kubeflow-userid: [email protected]"

Merge criteria:

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

• [X] The commits have meaningful messages
• [ ] Automated tests are provided as part of the PR for major new functionalities; testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• [X] The developer has manually tested the changes and verified that the changes work.
• [X] Code changes follow the kubeflow contribution guidelines.