Migration to typescript: first step

Add vue cli typescript support
Rename .js to .ts
Use class and annotations in App and NavBar
Add tslint

js/src/graphql/category.ts

@@ -0,0 +1,29 @@
+import gql from 'graphql-tag';
+
+export const FETCH_CATEGORIES = gql`
+query {
+    categories {
+        id,
+        title,
+        description,
+        picture {
+            url,
+        },
+   }
+}
+`;
+
+export const CREATE_CATEGORY = gql`
+    mutation createCategory($title: String!, $description: String!, $picture: Upload!) {
+        createCategory(title: $title, description: $description, picture: $picture) {
+            id,
+            title,
+            description,
+            picture {
+                url,
+                url_thumbnail
+            },
+        },
+    },
+
+`;