Quick import should work if DOI is included

From jabref created by koppor: JabRef/jabref#9821

1. Open "Import new entry from Id"
   
2. Paste https://www.scitepress.org/Link.aspx?doi=10.5220/0010404301780189
3. Click on the arrow on the right to trigger the fetch.

Expected result: Entry found

Actual result: No entry found

One can find the entry when searching for 10.5220/0010404301780189

There needs to be implemented a heuristic at the CompositeIdFetcher. Before passing the DOI to the DOI parser, a) existence of ?doi= needs to be checked, b) if yes, that part removed. Then passed to DOI.parse

/src/main/java/org/jabref/logic/importer/CompositeIdFetcher.java#L23

        Optional<DOI> doi = DOI.parse(identifier);

Test-enabling: Heuristics as own method. This method needs to be tested. Method can be "package private".

With that being implemented, https://github.com/JabRef/jabref/issues/7575 can also be fixed (howto at https://github.com/JabRef/jabref/issues/7575#issuecomment-1529055712).

Read src/main/java/org/jabref/logic/importer/CompositeIdFetcher.java at the DOI.parse call and inspect the existing tests for this fetcher. Run the relevant importer tests, then verify that a URL containing ?doi=... resolves to the same entry as the bare DOI and that the heuristic is covered by a focused test.