Allow compatible type when targetting object types in linter

[Lulu13022002]

Closes #50

This removes the unpickable type check and instead just check for compatible usage later which allow to not fail at the first linter issue. It might be interesting to extend this to support primitive too with their boxed equivalent later.
It effectively now match the implementation which never really respected this part of the specs: https://github.com/Vineflower/unpick-parser/blob/main/spec.md#targets

I didn't find any jdk/asm example for the target_field test so that is still pending.

[Earthcomputer]

I don't fully understand this change yet but I find it concerning that that test has been removed, that's an important check. Also, the spec does not allow for CharSequence to be unpicked, so it's a spec issue -- see the bullet point on compatible types in the targets section. Maybe something can be added to the spec about CharSequence specifically, and then we can solve this.

[Lulu13022002]

CharSequence is still not allowed as a group data type and will fails in the parser. This expand the later check to allow CharSequence to be used in target definitions (when the declared group is a String). But it's not specific to CharSequence the example provided in the linked issue should work for Object/Serializable and whatever type fitting a String.