Streamline FingerprintPatcher

[thiemowmde]

This streamlines the implementation and avoids calling the methods Fingerprint::setLabels, setDescriptions and setAliasGroups.

• Instead of turning the Term/AliasGroupLists into arrays, diffing and patching these arrays, and then turning them back into completely new lists of Term/AliasGroup objects, the patcher now does what it's name suggests: apply the patch. Done.
• This refactoring makes it very easy to turn this patcher into separate Label-, Description- and AliasGroupPatchers when we need them (see Introduce provider interfaces for labels, descriptions and aliases WikibaseDataModel#513 and Add interfaces to Item and Property WikibaseDataModel#632).

Missing:

• Refactor alias patching the same way. Done.
• Add tests. Lots and lots of them. All the conflicts are currently not tested! Done.
• Split code. Bad nesting. Done.

Bug: T78298

[thiemowmde]

I did an additional benchmark. Memory usage is unaffected. Runtime drops from 500ms to 200ms in my worst case test.

[brightbyte]

Removing milestone after discussion with Thiemo. This is a non-critical refactoring.

[JeroenDeDauw]

It's somewhat unfortunate to have to write custom patching code like this. I can see the benefits, though to me it's unclear if those outweigh the drawbacks. Don't let that stop you though, if you think this is better and worth the time, then go for it.

[thiemowmde]

Rebased on top of #124.

[thiemowmde]

Note: This whole method could be replaced with a ListPatcher call, but this needs wmde/Diff#65.