Auto-sync CSL Bibliography feature

[subhramit]

Closes subhramit#26
Follow-up to: #11577

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.

[subhramit]

Note that this feature does not work for JStyles, and not as a consequence of any change made during the CSL4LibreOffice project. [Tested using JabRef 5.13 stable]
We will need to fix this for JStyles separately. I have filed an issue (#11684).
I did not fix it in this PR as it will require diving slightly deeper on how syncOptions are used - the code for JStyles is, as usual, more complex.

I wanted it to at least be there for CSL for the 6.0-alpha version.

[ThiloteE]

I approve too.