Moved frontend of REST Mock to frontend container (solves #168)

Co-authored-by: Adam Bem <adam.bem@zoho.eu>
Reviewed-on: #186
Reviewed-by: Mikolaj Widla <widlam@noreply.example.com>

Frontend/assets/css/tools/mock/main.css

@@ -0,0 +1,4 @@
+.overflowedTableContent {
+    max-height: 750px;
+    overflow: scroll;
+}