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

app/views/layouts/auth.html.haml

@@ -6,7 +6,7 @@
     .logo-container
       %h1
         = link_to root_path do
-          = svg_logo_full
+          = logo_as_symbol(:wordmark)
 
     .form-container
       = render 'flashes'