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/javascript/packs/mailer.js

@@ -1 +1,3 @@
 require('../styles/mailer.scss');
+
+require.context('../icons');