Revert "Get rid of obsolete /search/hashtag page"

This reverts commit ec19c732e5678544d8dfd50c25f2c33e5aeb217e.

Ok, native module URL cannot parse relative URLs. It ensures that all parts
of the URL are present. So I'll revert this to get the ball rolling. We
can refactor out the obsolete page later on.

FYI @Tirokk

webapp/components/Editor/Editor.vue

@@ -491,8 +491,6 @@ export default {
     // we have to replace our suggestion text with a mention
     // so it's important to pass also the position of your suggestion text
     selectItem(item) {
-      const searchUrl = new URL('/')
-      searchUrl.searchParams.set('hashtag', item.name)
       const typeAttrs = {
         mention: {
           // TODO: use router here
@@ -501,7 +499,7 @@ export default {
         },
         hashtag: {
           // TODO: Fill up with input hashtag in search field
-          url: searchUrl.href,
+          url: `/search/hashtag/${item.name}`,
           label: item.name,
         },
       }

webapp/components/FilterMenu/FilterMenu.vue

@@ -49,7 +49,7 @@
 export default {
   props: {
     user: { type: Object, required: true },
-    hashtag: { type: String, default: null },
+    hashtag: { type: Object, default: null },
   },
   data() {
     return {

webapp/pages/search/hashtag/_id.vue

@@ -0,0 +1,12 @@
+<template>
+  <div></div>
+</template>
+
+<script>
+export default {
+  mounted() {
+    const { id: hashtag } = this.$route.params
+    this.$router.push({ path: '/', query: { hashtag } })
+  },
+}
+</script>