[5.1] Fix TinyMCE media button, insert link bug

[Fedik]

Pull Request for Issue #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:
• No documentation changes for docs.joomla.org needed
• Pull Request link for manual.joomla.org:
• No documentation changes for manual.joomla.org needed

[Quy]

I have tested this item ✅ successfully on 6339fe1

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[carlitorweb]

I have tested this item ✅ successfully on 6339fe1

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43374.}

[Quy]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43374.}