Refs #13930

Supesedes #13625

• Moves tests of lastAuthor from CitationKeyGeneratorTest to BracketedPatternTest
• Fixes typo and broken link in javadoc

I used single quotation marks that were not strictly necessary in the @CsvSource I added. This matches the style of the file, but I would be happy to remove them.

Steps to test

./gradlew :jablib:test --tests org.jabref.logic.citationkeypattern.BracketedPatternTest

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.