Feature: Add ability to drag and drop images to MarkdownEditor

[ganesh-vk]

Closes #10559

I've looked at the JavaFX documentation for dragging and dropping events and think I'm doing everything correctly. However I cannot seem to trigger the DRAG_DROPPED event at all. I've tried to debug and the DRAG_OVER event is being triggered everytime but the dropping isn't working. Please let me know what I should try to fix this.

Steps to test

Mandatory checks

• I own the copyright of the code submitted and I license it under the MIT license
• I manually tested my changes in running JabRef (always required)
• [/] I added JUnit tests for changes (if applicable)
• I added screenshots in the PR description (if change is visible to the user)
• I described the change in CHANGELOG.md in a way that is understandable for the average user (if change is visible to the user)
• I checked the user documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request updating file(s) in https://github.com/JabRef/user-documentation/tree/main/en.

[Siedlerchr]

Which OS are you using? Windows? Mac? Linux?

[ganesh-vk]

I'm using Linux (Fedora)

[koppor]

I've looked at the JavaFX documentation for dragging and dropping events and think I'm doing everything correctly. However I cannot seem to trigger the DRAG_DROPPED event at all.

Do a breakpoint at org.jabref.gui.fieldeditors.LinkedFilesEditor#handleOnDragDropped - and drop a file into the linked files editor (which is part of the Entry Editor)