Prefer nuxt-link component over events

@Tirokk I believe the Logo should also reset the search and filter
settings. However, even the previous implementation did not behave in
that way. A click on the logo will bring you back to the index page but
it will not reset your filter settings.

I fixed this because `$router.push(...).go(...)` will certainly throw an
null pointer error.

webapp/layouts/default.vue

@@ -5,9 +5,9 @@
         <div>
           <ds-flex>
             <ds-flex-item :width="{ base: '49px', md: '150px' }">
-              <a @click="$router.push('/').go('/')">
+              <nuxt-link to="/">
                 <ds-logo />
-              </a>
+              </nuxt-link>
             </ds-flex-item>
             <ds-flex-item>
               <div id="nav-search-box" v-on:click="unfolded" @blur.capture="foldedup">