Add CMS page to Hubspot

[madebyisaacr]

Description

This pull request replaces the events button in the HubSpot plugin with a CMS button. The CMS page shows you the HubSpot collections in your project and has a button to create a new one using createManagedCollection. When you click on a collection, it opens it with navigateTo.

The events button that was there before never did anything - it just showed a message saying "The events feature will be out soon".

CMS button in bottom left corner:

First collection button shows the hover state:

Empty state:

Closes #520

Testing

• Click CMS button in main menu.
• Click new collection button to test collection creation.
• Return to the plugin, and check if all HubSpot collections are shown in the list.
• Click a collection button to navigate to it.
• Ensure permissions checking works by testing the plugin in a project where you do not have access to create collections, and verify the button is disabled.