improve unlinked files dialog

[agondekova]

Description of changes:

I modified the display of file paths in the "File" column so that relative paths, starting from the directory specified in the "Directory" field, are shown instead of full absolute paths. I also added the ability to resize the columns in the table, making them customizable for the user. Additionally, I changed the alignment of the text in the column, which was previously aligned to the right, to the left, as described in the issue, to ensure proper display when the text doesn’t fit within the available space.

This change improves the clarity and flexibility when working with the table.

Closes #11878.

Mandatory checks

• I own the copyright of the code submitted and I licence it under the MIT license
• Change in CHANGELOG.md described in a way that is understandable for the average user (if change is visible to the user)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked 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 to the documentation repository.

[github-actions]

Your code currently does not meet JabRef's code guidelines.
We use OpenRewrite to ensure "modern" Java coding practices.
The issues found can be automatically fixed.
Please execute the gradle task rewriteRun, check the results, commit, and push.

You can check the detailed error output by navigating to your pull request, selecting the tab "Checks", section "Tests" (on the left), subsection "OpenRewrite".

[Siedlerchr]

codewise looks good already, just some small improvements.
will do a proper test tomorrow

[github-actions]

Your code currently does not meet JabRef's code guidelines.
We use OpenRewrite to ensure "modern" Java coding practices.
The issues found can be automatically fixed.
Please execute the gradle task rewriteRun, check the results, commit, and push.

You can check the detailed error output by navigating to your pull request, selecting the tab "Checks", section "Tests" (on the left), subsection "OpenRewrite".

[github-actions]

Your code currently does not meet JabRef's code guidelines.
We use OpenRewrite to ensure "modern" Java coding practices.
The issues found can be automatically fixed.
Please execute the gradle task rewriteRun, check the results, commit, and push.

You can check the detailed error output by navigating to your pull request, selecting the tab "Checks", section "Tests" (on the left), subsection "OpenRewrite".

[Siedlerchr]

tested, looks good

[subhramit]

Please remove the obvious comments from your AI-generated code (the code relays the information already) (or modify them to keep the useful parts).
We can merge after this.

Remember: If you are to spend time commenting - commenting the main code is always more important for developers than comments in the test class.

obsolete now