[UX] Replace 'Create' button with menu

### Describe the feature you'd like to request

As an user, I want to be able to easily create new hypercerts, collections, and blueprints, so that I can manage my impact claims as easy as possible

### Describe the solution you'd like

Replace the Create button with a dropdown menu that allows for creating:

- Hypercert
- Collection
- Blueprint

### Describe alternatives you've considered

.