Fix I18n component accessibility

client/src/components/InterfaceLanguageDropdown.vue

@@ -1,12 +1,13 @@
 <template>
   <div class="interface-language-dropdown">
+    <button @click="toggleShow()">
       <img
         :title="imgTitle"
         class="interface-language"
         src="/img/interface-languages.svg"
         alt="Change interface language"
-      @click="toggleShow()"
       >
+    </button>
 
     <div
       v-if="showMenu"
@@ -57,9 +58,15 @@
       }
     },
 
+    mounted () {
+      document.addEventListener('keydown', event => {
+        if (event.key === 'Escape') this.showMenu = false
+      });
+    },
+
     methods: {
       toggleShow () {
-        this.showMenu = !this.showMenu;
+        this.showMenu = !this.showMenu
       },
 
       buildLanguageRoute (locale: string | number) {
@@ -73,10 +80,18 @@
   @import '../scss/_variables';
 
   .interface-language-dropdown {
+
+    > button {
+      border: none;
+      padding: 0;
+      background: transparent;
+      width: inherit;
+
       img {
         cursor: pointer;
         opacity: .7;
       }
+    }
 
     .menu {
       z-index: 10;