[5.x] Plugin relies on loading order for custom plugins

Description

This plugin immediately registers custom plugins' namespaces in its own init function:
https://github.com/craftcms/ckeditor/blob/0abec0bba0c90c39bb586c983c9b51d57d24010b/src/Plugin.php#L71-L76

Given that Craft loads plugins in alphabetical order (as of https://github.com/craftcms/cms/commit/2540de56f99d9f3b38bbc14070c433ccf00b56ab), this prevents any custom CKEditor plugins with a name alphabetically past CKEditor's own (e.g. ckeditor-some-plugin) from registering themselves.

Steps to reproduce

1. Set up a new CKEditor plugin with a handle alphabetically past CKEditor's (e.g. ckeditor-test)
2. Install it
3. Notice that it never shows up in the page's importmap and the plugin's init (where you must register the CKEditor package) is called after CKEditor's own init

A complete reproduction can be found here: https://github.com/lexisother/ckeditor-load-order-repro

Video

https://github.com/user-attachments/assets/d8a21a73-b070-46d8-9141-eacb6c58b22d

Additional info

• Craft version: 5.11.1
• PHP version: 8.3
• Database driver & version: MySQL 8.0.40
• Plugins & versions: CKEditor 5.7.0

Start at src/Plugin.php lines 71-76 and compare its init behavior with the loading sequence described in the issue. Use the linked ckeditor-load-order-repro to verify a custom plugin such as ckeditor-test is included in the page importmap and initialized successfully regardless of alphabetical order.