feat(theme): multiple values for nb-(except-)for-theme (#1218)

Added mixins for both `nb-for-theme` and `nb-except-for-theme` to work with multiple theme names with same content style

src/framework/theme/styles/_theming.scss

@@ -144,13 +144,31 @@ $nb-themes-export: () !global;
     @content;
   }
 }
+
+// Add content for theme into a list of themes
+@mixin nb-for-themes($names...) {
+  @each $name in $names {
+    @include nb-for-theme($name) {
+      @content;
+    }
+  }
+}
 
 @mixin nb-except-theme($name) {
   @if ($theme-name != $name) {
     @content;
   }
 }
 
+// Add content except for theme into a list of themes
+@mixin nb-except-for-themes($names...) {
+  @each $name in $names {
+    @include nb-except-theme($name) {
+      @content;
+    }
+  }
+}
+
 // TODO: another mixing for the almost same thing
 @mixin nb-install-root-component() {
   @warn '`nb-install-root-component` is depricated, replace with `nb-install-component`, as `body` is root element now';