Move model registry UI away from modals for creation

Move model registry UI away from modals for model and version creation

Context

We have started using modals for creating models, versions and artifacts.

Modals are often considered detrimental to UI because they interrupt the user's workflow, require immediate attention, block access to background content, and can lead to users forgetting their original tasks, making them less ideal than using separate pages for many interactions.

Related: #463667 (closed)

Solution

• Move model and version creation away from modals
• Get rid of the old code for non-modals