Implement Syncback to support converting Roblox files to a Rojo project (#937)

This is a very large commit.
Consider checking the linked PR for more information.

src/web/ui.rs

@@ -165,6 +165,7 @@ impl UiService {
                     <div>"specified_id: " { format!("{:?}", metadata.specified_id) } </div>
                     <div>"ignore_unknown_instances: " { metadata.ignore_unknown_instances.to_string() }</div>
                     <div>"instigating source: " { format!("{:?}", metadata.instigating_source) }</div>
+                    <div>"middleware: " { format!("{:?}", metadata.middleware) }</div>
                     { relevant_paths }
                 </>
             };