Generate journal-list.mv on build

[koppor]

This PR removes the binary files journal-lists.mv from the source code. It is generated during the build.

This PR must be merged using a merge commit. Otherwise git subtree won't work.

Refs koppor#360 (which asks for abbreviations also working for conferences)

We now DO NOT include the *.csv files in the repository. We also REMOVED the CSL files, and use git git submodules there, too.

This should reduce our merge conflicts.

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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]

Think of

    show-progress: 'false'

for git checkout outs

[koppor]

IDK why the following warning is displayed. I filed an issue at actions/checkout#1446