Add Tailwind button for save+cancel

- remove custom styles
- add new button styles based on Tailwind classes using @apply
- extend config to allow hover:ring-blue-200 and such
- update the js-files to use new classes

- Only unsure about the `.review-form .save-non-active`, this might need additional Tailwind helper classes in this specific situation. Don't know where it shows up, so could not test.

UI/Popup/EditableTagRendering.ts

@@ -74,7 +74,7 @@ export default class EditableTagRendering extends UIElement {
             // And at last, set up the skip button
             const cancelbutton =
                 Translations.t.general.cancel.Clone()
-                    .SetClass("cancel")
+                    .SetClass("btn btn-secondary mr-3")
                     .onClick(() => {
                         self._editMode.setData(false)
                     });