Implement scrollable warning messages in alert boxes

[garymejia]

Added a scrollbar to the "Open library error" popup window to prevent extension beyond the screen when handling large bib files with citation errors. This enhancement ensures the window remains within the screen boundaries.
Closes #10674

Mandatory checks

• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• 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.

[koppor]

Thank you for taking initiative! - Please ensure that you have JabRef's code style settings in place. Checkstyle complains about wrong import order.

I wonder whether there can be tests added?

At least for getErrorMessages() there should be a test.

Reason: This is a logic module - and one or more tests can help enhancing that core funtionality.

[garymejia]

I'll work on getting a test setup soon. Let me know if I committed incorrectly. Still trying to get a hang of this haha.

[koppor]

@garymejia Thank you for the PR. We will merge it. You can add test cases as a follow-up if you want!