Enable/Disable the undo and redo toolbar/menu buttons correctly

[HoussemNasri]

Closes #8807

Screenshots

• Redo button is disabled
  

• Undo button is disabled
  

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.

[Siedlerchr]

from my side looks good but better have olly and carl take a look s well

[koppor]

This will add a listener after each tab change. The old listener should be removed. Otherwise, memory consumption will increase IMHO.