refactor checkPermissionsForDatasetExtended

[omkar-ethz]

https://github.com/SciCatProject/backend/pull/2887/changes#diff-ea81e2d2886b2ed8094201f579f2be688074296f30b541b9f5c3240bed32d12cR248 needs this method, but requires a cross controller dependency.

https://github.com/SciCatProject/backend/pull/2888/changes#diff-a32900a0e4a4a230fb83725de0a2a2d4de5b1d40307857fd6948ac138d812818R63 also needs this, but duplicates the method instead of cross-controller dependency.

Refactor it to a util / common helper, and fix these inconsitencies.

[omkar-ethz]

FYI @HayenNico to track the code-style issues discussed earlier.

[HayenNico]

@omkar-ethz Adding this to the authorization rework project - I ultimately want to put as much of this controller-level auth logic into common modules as possible to reduce duplication.
Not a blocker for a shorter-term solution in case you're already working on something