Revert "Refactor: replace default slots"

This reverts commit f1e308074bc33e6762431f90f335ed849776f4d9.

  Let's take this one at a time...

webapp/components/CommentForm/CommentForm.vue

@@ -1,6 +1,6 @@
 <template>
   <ds-form v-model="form" @submit="handleSubmit" class="comment-form">
-    <template v-slot="{ errors }">
+    <template slot-scope="{ errors }">
       <base-card>
         <hc-editor ref="editor" :users="users" :value="form.content" @input="updateEditorContent" />
         <div class="buttons">

webapp/components/ContentMenu/ContentMenu.vue

@@ -1,6 +1,6 @@
 <template>
   <dropdown class="content-menu" :placement="placement" offset="5">
-    <template v-slot="{ toggleMenu }">
+    <template slot="default" slot-scope="{ toggleMenu }">
       <slot name="button" :toggleMenu="toggleMenu">
         <base-button
           data-test="content-menu-button"

webapp/components/ContributionForm/ContributionForm.vue

@@ -6,7 +6,7 @@
     :schema="formSchema"
     @submit="submit"
   >
-    <template v-slot="{ errors }">
+    <template slot-scope="{ errors }">
       <base-card>
         <template #heroImage>
           <img

webapp/components/DropdownFilter/DropdownFilter.vue

@@ -1,8 +1,9 @@
 <template>
   <dropdown offset="8">
-    <template v-slot="{ toggleMenu }">
     <a
       :v-model="selected"
+      slot="default"
+      slot-scope="{ toggleMenu }"
       name="dropdown"
       class="dropdown-filter"
       href="#"
@@ -12,7 +13,6 @@
       <label class="label" for="dropdown">{{ selected }}</label>
       <base-icon class="dropdown-arrow" name="angle-down" />
     </a>
-    </template>
     <ds-menu
       #popover="{ toggleMenu }"
       class="dropdown-menu-popover"

webapp/components/FilterPosts/FilterPosts.vue

@@ -1,10 +1,11 @@
 <template>
   <dropdown ref="menu" :placement="placement" :offset="offset">
     <base-button
-      v-slot="{ toggleMenu }"
+      slot="default"
       icon="filter"
       :filled="filterActive"
       :ghost="!filterActive"
+      slot-scope="{ toggleMenu }"
       @click.prevent="toggleMenu()"
     >
       <base-icon class="dropdown-arrow" name="angle-down" />

webapp/components/LocaleSwitch/LocaleSwitch.vue

@@ -1,8 +1,9 @@
 <template>
   <client-only>
     <dropdown ref="menu" :placement="placement" :offset="offset">
-      <template v-slot="{ toggleMenu }">
       <a
+        slot="default"
+        slot-scope="{ toggleMenu }"
         class="locale-menu"
         href="#"
         @click.prevent="toggleMenu()"
@@ -11,7 +12,6 @@
         <span class="label">{{ current.code.toUpperCase() }}</span>
         <base-icon class="dropdown-arrow" name="angle-down" />
       </a>
-      </template>
       <ds-menu
         #popover="{ toggleMenu }"
         class="locale-menu-popover"

webapp/components/NotificationMenu/NotificationMenu.vue

@@ -7,7 +7,7 @@
     <base-button icon="bell" ghost circle />
   </nuxt-link>
   <dropdown v-else class="notifications-menu" offset="8" :placement="placement">
-    <template v-slot="{ toggleMenu }">
+    <template slot="default" slot-scope="{ toggleMenu }">
       <base-button @click="toggleMenu" ghost circle>
         <counter-icon icon="bell" :count="unreadNotificationsCount" danger />
       </base-button>

webapp/components/Password/Change.vue

@@ -1,6 +1,6 @@
 <template>
   <ds-form v-model="formData" :schema="formSchema" @submit="handleSubmit">
-    <template v-slot="{ errors }">
+    <template slot-scope="{ errors }">
       <ds-input
         id="oldPassword"
         model="oldPassword"

webapp/components/PasswordReset/ChangePassword.vue

@@ -7,7 +7,7 @@
       @submit="handleSubmitPassword"
       class="change-password"
     >
-      <template v-slot="{ errors }">
+      <template slot-scope="{ errors }">
         <ds-input
           id="password"
           model="password"

webapp/pages/settings/index.vue

@@ -1,6 +1,6 @@
 <template>
   <ds-form v-model="form" :schema="formSchema" @submit="submit">
-    <template v-slot="{ errors }">
+    <template slot-scope="{ errors }">
       <base-card>
         <h2 class="title">{{ $t('settings.data.name') }}</h2>
         <ds-input

webapp/pages/settings/my-email-address/enter-nonce.vue

@@ -1,6 +1,6 @@
 <template>
   <ds-form v-model="form" :schema="formSchema" @submit="submit">
-    <template v-slot="{ errors }">
+    <template slot-scope="{ errors }">
       <base-card>
         <h2 class="title">{{ $t('settings.email.name') }}</h2>
         <ds-input

webapp/pages/settings/my-email-address/index.vue

@@ -6,7 +6,7 @@
     <ds-text v-html="submitMessage" />
   </base-card>
   <ds-form v-else v-model="form" :schema="formSchema" @submit="submit">
-    <template v-slot="{ errors }">
+    <template slot-scope="{ errors }">
       <base-card>
         <h2 class="title">{{ $t('settings.email.name') }}</h2>
         <ds-input