[rebase, 029e6fe] Multiple categories are all shown in first category tab on first open

[danowar2k]

Describe the bug
When you define multiple course element categories with several components and open a page with a tiny editor on it, and open the elements dialog, it has multiple tabs for the categories, the first tab is selected and shows all components of all categories. When you then select another category, only the components for that category are shown. Going back to the first, only the correct components are shown.

What may be important: It doesn't seem to happen when you still have the original components shipped with the plugin.

To Reproduce
Steps to reproduce the behavior:

1. Create two categories with one or more components
2. Delete all categories and components which shipped with the plugin
3. Go to a page containing a editor
4. Click on "Insert Course Element"
5. See that the first category is selected but all components of all categories are shown

Expected behavior
On opening the editor, it should always only show the components of the currently selected category.

Screenshots

Desktop (please complete the following information):

• OS: Windows 11
• Browser: Chrome
• Version: 140.0.7339.128

[minhduchoang195]

I created the PR #41 to solve this issue.