Change brand color and logotypes (#18592)

- Add rake task for generating Apple/Android icons and favicons from SVG
- Add rake task for generating PNG icons and logos for e-mails from SVG
- Remove obsolete Microsoft icons and configuration
- Remove PWA shortcut icons

spec/helpers/application_helper_spec.rb

@@ -59,13 +59,6 @@ describe ApplicationHelper do
     end
   end
 
-  describe 'favicon_path' do
-    it 'returns /favicon.ico on production environment' do
-      expect(Rails.env).to receive(:production?).and_return(true)
-      expect(helper.favicon_path).to eq '/favicon.ico'
-    end
-  end
-
   describe 'open_registrations?' do
     it 'returns true when open for registrations' do
       without_partial_double_verification do