TNL-6920 Component Editor Efficiency Improvements

* Enlarges component modal for easier editing
* Allows display name to be edited in place
* Improves markdown button labeling
* Moves markdown cheatsheet to the edit modal, for quick reference

common/test/acceptance/pages/studio/problem_editor.py

@@ -28,7 +28,7 @@ class ProblemXBlockEditorView(XBlockEditorView):
         """
         If editing, set the value of a field.
         """
-        selector = u'.xblock-studio_view li.field label:contains("{}") + input'.format(field_display_name)
+        selector = u'.metadata_edit li.field label:contains("{}") + input'.format(field_display_name)
         script = "$(arguments[0]).val(arguments[1]).change();"
         self.browser.execute_script(script, selector, field_value)