Add CLI tests for jabref

[ravatex]

Is your suggestion for improvement related to a problem? Please describe.
Currently there is almost no testing for the actual CLI functionality, this caused jabref pseudonymize to have some easy to solve bugs that should have been caught by testing.

Describe the solution you'd like
There is already a test for ArgumentProcessor I propose we introduce tests similar to those for ArgumentProcessor for the ten other classes present. Additionally, we can create some abstraction that makes creating tests for the CLI more developer friendly.

[subhramit]

bugs that should have been caught by testing

Refs example #14122 and corresponding PR.

[ravatex]

/assign-me

[github-actions]

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[ravatex]

Do you think this should be a single PR? @subhramit
Given I will have to add 9 new test classes, should I split this somehow or should we bite the bullet and do a single PR with all the new tests.

[subhramit]

Do you think this should be a single PR? @subhramit
Given I will have to add 9 new test classes, should I split this somehow or should we bite the bullet and do a single PR with all the new tests.

You do make a good point about scope since it is just not a "single" component we are adding tests for, so usually it depends.
However, since all the present CLI functionality is known and well defined, and there are no heavy logic changes, I assume one PR should be easy enough to review.