Move phases and actions out of the budget form

Having links in the middle of a form distracts users from the task of
filling in the form, and following a link before submitting the form
will mean whatever has been filled in is lost.

And the budgets form is already very long and hard to fill in. Having
the phases table in the middle of it made it even harder. And, since
we're planning to add the option to manage groups and headings from the
same page, it's better to have a dedicated page for the form.

app/components/admin/budgets/calculate_winners_button_component.rb

@@ -21,10 +21,6 @@ class Admin::Budgets::CalculateWinnersButtonComponent < ApplicationComponent
     end
 
     def html_class
-      if from_investments
-        "button hollow float-right clear"
-      else
-        "button hollow"
-      end
+      "button hollow float-right clear" if from_investments
     end
 end