Issue when adding media with multiple instances in the same block

[markhollis]

Describe the bug
When adding media to a block of content containing multiple instances of the CKEditor, it will always add to the last block of the chain.

To Reproduce
Steps to reproduce the behavior:

1. Add multiple CKEditor instances in a single Content Type.
2. Click on 'Add Media' and add an image to the first CKEditor in the chain.
3. See that the image has now appeared in the last CKEditor in the chain.

Expected behavior
The media should add to the same instance which it is added to.

Screenshots

Plugin: strapi-plugin-ckeditor: "^3.0.5"

Additional context
There may be an issue with a global or singleton reference to the media lib plugin: https://github.com/nshenderov/strapi-plugin-ckeditor/blob/master/admin/src/components/Input/plugins/StrapiMediaLib.js

Regarding the global reference to plugins here, it is possible each editor inits a new plugin instance, but there's a global singleton reference and the last one is used.