Added abstract category class to trait_manager

[amirrahmani76]

An abstract category class was added to the trait_manager, like the block_manager, and refactoring the block_manager.
I've tried to fix this: (add category on traits)

Usage:

    editor.DomComponents.addType('text', {
      isComponent: (el) => el.tagName == 'text',
      model: {
        defaults: {
          traits: [
            {
              label: 'My',
              type: 'text',
              name: 'me',
              category: { id: 'general', label: 'General' },
            },

            {
              label: 'My trait3',
              type: 'text',
              name: 'text',
              category: { id: 'ito', label: 'Ito' },
            },
          ],
          attributes: { type: 'text', required: true },
        },
      },
    });

[mrshaone]

[artf]

@amirrahmani76 I did some cleanup before merge but overall it's a good PR. Thank you 🙏