[TASK] Modify Secrets Creation Modal

[thaorell]

Certification

• I certify I am an Epic Owner for Kubeflow Notebooks 2.0 and expected to create planning-related issues.

Description

We need to rework the "Create New Secret" modal/view to align with the newly defined Secrets stubs. This will provide an intuitive UI based to create a secret.

Acceptance Criteria

• The user must see fields for: Secret Name and a simple interface for adding Opaque secrets https://kubernetes.io/docs/concepts/configuration/secret/#opaque-secrets
• Clicking the submit button triggers an immediate POST request to the /api/v1/secrets/{namespace} endpoint
• (BONUS) Support Secrets file upload

[thaorell]

/area frontend
/area v2