Don't create custom elements in main and fix various small issues on tests (#747)

* Create custom elements when the runtime finishes loading

* Remove xfails and fix repl integration test

* Fix commented ignore

* Address Antonio's comments

* Fix bad rebase

* Make ure to wait for repl to be in attached state before asserting content

* Move createCustomeElement up so it runs before we close the loader, xfail flaky d3 test

* Fix xfail

pyscriptjs/src/runtime.ts

@@ -8,8 +8,9 @@ import {
     postInitializers,
     Initializer,
     scriptsQueue,
-    appConfig
-} from './stores'
+    appConfig,
+} from './stores';
+import { createCustomElements } from './components/elements';
 import type { PyScript } from './components/pyscript';
 import { getLogger } from './logger';
 
@@ -167,6 +168,9 @@ export abstract class Runtime extends Object {
         // now we call all post initializers AFTER we actually executed all page scripts
         loader?.log('Running post initializers...');
 
+        // Finally create the custom elements for pyscript such as pybutton
+        createCustomElements();
+
         if (appConfig_ && appConfig_.autoclose_loader) {
             loader?.close();
         }