Better heuristics for the title and the author (#11999)

[alexvsf0]

Closes _____
Closes #11999

I wrote a better heuristic for the title and for the authors, which gives for the documents I tried the right title and authors.

The next step is to correct the abstract, because it doesn't understand if there are multiple columns.

Steps to test

After launching jabref, create a new library, import a pdf, and then there will be different options for the title and the authors. The first colmun uses metadata, and the second one uses pdf's content, which is the part I modificated. This second column should correspond to the real title and the real authors of the document.

Mandatory checks

• I own the copyright of the code submitted and I license it under the MIT license
• I manually tested my changes in running JabRef (always required)
• [/] I added JUnit tests for changes (if applicable)
• [/] I added screenshots in the PR description (if change is visible to the user)
• I described the change in CHANGELOG.md in a way that is understandable for the average user (if change is visible to the user)
• I checked the user 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 updating file(s) in https://github.com/JabRef/user-documentation/tree/main/en.

[github-actions]

Hey @alexvsf0!

Thank you for contributing to JabRef! Your help is truly appreciated ❤️.

We have automatic checks in place, based on which you will soon get automated feedback if any of them are failing. We also use TragBot with custom rules that scans your changes and provides some preliminary comments, before a maintainer takes a look. TragBot is still learning, and may not always be accurate. In the "Files changed" tab, you can go through its comments and just click on "Resolve conversation" if you are sure that it is incorrect, or comment on the conversation if you are doubtful.

Please re-check our contribution guide in case of any other doubts related to our contribution workflow.

[koppor]

Thank you for submitting an early draft.

I wonder why no JUnit test cases are added. How could you test your code?

At least jablib/src/main/java/org/jabref/logic/importer/util/AuthorHeuristics.java need to have tests added. The other class, too. Please take care of branch coverage.

[jabref-machine]

JUnit tests of jablib are failing. You can see which checks are failing by locating the box "Some checks were not successful" on the pull request page. To see the test output, locate "Source Code Tests / Unit tests (pull_request)" and click on it.

You can then run these tests in IntelliJ to reproduce the failing tests locally. We offer a quick test running howto in the section Final build system checks in our setup guide.

[koppor]

Please add tests.

[github-actions]

Your pull request conflicts with the target branch.

Please merge with your code.
For a step-by-step guide to resolve merge conflicts, see https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/addressing-merge-conflicts/resolving-a-merge-conflict-using-the-command-line.