Not found page with html and moved utils into index and split http requests to separate files.

Static dir for hosting html files.

Helper function for loading HTML.

Changed location where openapi.html is generated and updated dockerfile

http/index.http

@@ -0,0 +1,17 @@
+### GET index page
+
+GET {{url}}
+
+### GET OpenAPI page
+
+GET {{url}}/openapi
+
+### GET should fallback to 404 page
+
+GET {{url}}/something-that-does-not-exist
+
+> {%
+    client.test("Response status is 404", () => {
+        client.assert(response.status === 404, "Response status is not 404");
+    });
+%}