Add Swedish sv-SE (already in simple-spellchecker) (#1483)

* Add Swedish sv-SE (already in simple-spellchecker)

* Remove spaces in empty lines

* Add some sv-SE test for spellchecker

Co-authored-by: Peter Johansson <peter.johansson@havochvatten.se>

src/main/SpellChecker.js

@@ -119,6 +119,9 @@ SpellChecker.getSpellCheckerLocale = (electronLocale) => {
   if (electronLocale.match(/^ru-?/)) {
     return 'ru-RU';
   }
+  if (electronLocale.match(/^sv-?/)) {
+    return 'sv-SE';
+  }
   if (electronLocale.match(/^uk-?/)) {
     return 'uk-UA';
   }