added description string to the themeloader, this is then used to dis… (#5584)

* added description string to the themeloader, this is then used to display the description of the theme after applying a new theme in the preferences.

* removed description string from themeloader, instead put the theme description inside the localization string

* added a dot to the restart message string.

* added locale strings to the english language file

Author: carlg0ransson

src/main/java/org/jabref/gui/preferences/AppearanceTabViewModel.java

@@ -81,10 +81,10 @@ public void storeSettings() {
         }
 
         if (themeLightProperty.getValue() && !preferences.get(JabRefPreferences.FX_THEME).equals(ThemeLoader.MAIN_CSS)) {
-            restartWarnings.add(Localization.lang("Theme changed:") + " " + ThemeLoader.MAIN_CSS);
+            restartWarnings.add(Localization.lang("Theme changed to light theme."));
             preferences.put(JabRefPreferences.FX_THEME, ThemeLoader.MAIN_CSS);
         } else if (themeDarkProperty.getValue() && !preferences.get(JabRefPreferences.FX_THEME).equals(ThemeLoader.DARK_CSS)) {
-            restartWarnings.add(Localization.lang("Theme changed:") + " " + ThemeLoader.DARK_CSS);
+            restartWarnings.add(Localization.lang("Theme changed to dark theme."));
             preferences.put(JabRefPreferences.FX_THEME, ThemeLoader.DARK_CSS);
         }
     }

src/main/resources/l10n/JabRef_en.properties

@@ -2100,7 +2100,8 @@ Size\:=Size:
 Font\ settings=Font settings
 Override\ font\ settings=Override font settings
 Override\ font\ size=Override font size
-Theme\ changed\:=Theme changed\:
+Theme\ changed\ to\ dark\ theme.=Theme changed to dark theme.
+Theme\ changed\ to\ light\ theme.=Theme changed to light theme.
 You\ must\ enter\ an\ integer\ value\ higher\ than\ 8.=You must enter an integer value higher than 8.
 Letters\ after\ duplicate\ generated\ keys=Letters after duplicate generated keys
 Start\ on\ second\ duplicate\ key\ with\ letter\ A\ (a,\ b,\ ...)=Start on second duplicate key with letter A (a, b, ...)