Enable clearing of user avatar

dashboard/src/views/ProfileView.vue

@@ -80,6 +80,11 @@ async function onAvatarSubmit(file) {
   await refreshProfile();
 }
 
+async function onAvatarUnset() {
+  await profileModel.unsetAvatar();
+  await refreshProfile();
+}
+
 async function onPasswordChange() {
   passwordChangeDialog.value.open();
 }
@@ -211,7 +216,7 @@ onMounted(async () => {
 
       <div style="display: flex; flex-wrap: wrap; gap: 20px">
         <div style="width: 128px;">
-          <ImagePicker :src="profile.avatarUrl" fallback-src="/img/avatar-default-symbolic.svg" :disabled="config.profileLocked" :size="512" :save-handler="onAvatarSubmit" display-width="128px"/>
+          <ImagePicker :src="profile.avatarUrl" fallback-src="/img/avatar-default-symbolic.svg" :disabled="config.profileLocked" :size="512" :unset-handler="onAvatarUnset" :save-handler="onAvatarSubmit" display-width="128px"/>
         </div>
         <div style="flex-grow: 1;">
           <SettingsItem>