Add "New organization" button

We need to add a New organization button in two places:

1. The list view in Your work - Completed in Organization list view in "Your work" - build list (#417876 - closed)
2. The empty state on the Your work list view - Completed in Organization list view in "Your work" - build list (#417876 - closed)
3. The + dropdown in the main nav

The button should link to /-/organizations/new which will be built in Create organization - build form (#417878 - closed)