Add de_CH translation (#611)

Region-specific translation for German (Switzerland). 

Initiated from here: https://github.com/shoelace-style/shoelace/pull/609#issuecomment-987711804

src/translations/de_CH.ts

@@ -0,0 +1,20 @@
+import { registerTranslation } from '../utilities/localize';
+import type { Translation } from '../utilities/localize';
+
+const translation: Translation = {
+  $code: 'de_CH',
+  $name: 'Deutsch (Schweiz)',
+  $dir: 'ltr',
+
+  close: "Schliessen",
+  copy: 'Kopieren',
+  progress: 'Fortschritt',
+  scroll_to_end: 'Zum Ende scrollen',
+  scroll_to_start: 'Zum Anfang scrollen',
+  select_a_color_from_the_screen: "Wähle eine Farbe vom Bildschirm",
+  toggle_color_format: 'Farbformat umschalten'
+};
+
+registerTranslation(translation);
+
+export default translation;