fix: Render Word cloud block editor in libraries [FC-0076] (#36199)

* fix: Render Word cloud and conditional block editor

- The xmodule-type to render is MetadataOnlyEditingDescriptor
- The xmodule type `MetadataOnlyEditingDescriptor` renders a `<div>` with the block metadata in the `data-metadata` attribute. But is necessary to call `XBlockEditorView.xblockReady()` to run the scripts to build the editor using the metadata.
- To call XBlockEditorView.xblockReady() we need a specific require.config

* fix: Adding save and cancel button

* fix: save with studio_submit of conditional_block and word_cloud_block

* test: Tests for studio_submit of conditional and word cloud

* revert: Delete studio_submit of conditional block. It is not supported

* style: Fix lint

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Co-authored-by: Navin Karkera <navin@opencraft.com>

cms/static/js/views/xblock_editor.js

@@ -78,7 +78,7 @@ function($, _, gettext, BaseView, XBlockView, MetadataView, MetadataCollection)
                     el: metadataEditor,
                     collection: new MetadataCollection(models)
                 });
-                if (xblock.setMetadataEditor) {
+                if (xblock && xblock.setMetadataEditor) {
                     xblock.setMetadataEditor(metadataView);
                 }
             }