[5.1] Fix TinyMCE media button, insert link bug

[Fedik]

Pull Request for Issue https://github.com/joomla/joomla-cms/issues/43365

Summary of Changes

Fix inserting PDF in to TinyMCE as a link

Testing Instructions

Run npm install In TinyMCE editor try to insert a PDF file, using Media button

Actual result BEFORE applying this Pull Request

Nothing hapen. Browser console shows an error

Expected result AFTER applying this Pull Request

Link inserted

Link to documentations

Please select:

• [ ] Documentation link for docs.joomla.org:
• [x] No documentation changes for docs.joomla.org needed
• [ ] Pull Request link for manual.joomla.org:
• [x] No documentation changes for manual.joomla.org needed

[Quy]

I have tested this item :white_check_mark: successfully on 6339fe1313b4453df5a4d95b0e05b548c8486098

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[carlitorweb]

I have tested this item :white_check_mark: successfully on 6339fe1313b4453df5a4d95b0e05b548c8486098

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[Quy]

RTC

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[LadySolveig]

Thank you @Fedik and for testing @Quy @carlitorweb