Introduce component for FAB

aleksis/apps/alsijil/frontend/components/coursebook/absences/AbsenceCreationDialog.vue

 <template>
   <mobile-fullscreen-dialog v-model="popup" persistent>
     <template #activator="activator">
-      <create-button
-        style="z-index: 5"
+      <fab-button
         color="secondary"
         @click="popup = true"
         :disabled="popup"
-        fab
-        large
-        bottom
-        fixed
-        right
         :class="{
           'd-none': !checkPermission('alsijil.view_register_absence_rule'),
         }"
+        icon-text="$plus"
       >
         <v-icon>$plus</v-icon>
-      </create-button>
+      </fab-button>
     </template>
     <template #title>
       <div>
@@ -88,7 +83,7 @@
 import MobileFullscreenDialog from "aleksis.core/components/generic/dialogs/MobileFullscreenDialog.vue";
 import AbsenceCreationForm from "./AbsenceCreationForm.vue";
 import AbsenceCreationSummary from "./AbsenceCreationSummary.vue";
-import CreateButton from "aleksis.core/components/generic/buttons/CreateButton.vue";
+import FabButton from "aleksis.core/components/generic/buttons/FabButton.vue";
 import CancelButton from "aleksis.core/components/generic/buttons/CancelButton.vue";
 import SaveButton from "aleksis.core/components/generic/buttons/SaveButton.vue";
 import SecondaryActionButton from "aleksis.core/components/generic/buttons/SecondaryActionButton.vue";
@@ -104,10 +99,10 @@ export default {
     MobileFullscreenDialog,
     AbsenceCreationForm,
     AbsenceCreationSummary,
-    CreateButton,
     CancelButton,
     SaveButton,
     SecondaryActionButton,
+    FabButton,
   },
   mixins: [loadingMixin, mutateMixin, permissionsMixin],
   data() {