Adds UI to create MlModel

What does this MR do and why?

Adds a modal that allows the creation of a new machine learning model in the model registry

This MR depends on !140229 (merged)

Screenshots

	Before	After
Index page
New model page
New model with error

How to set up and validate locally

1. Enable the feature flag

   Feature.enable(:model_registry)

2. Navigate to gdk/<project>/-/ml/models. Click on Create model, this will navigate to the correct place

3. Type a name and a description, confirm create. It will navigate to the new model

4. Go back, and type the same name again. It should error.

Related to #387580 (closed)