Refactor stashbox package (#5699)

* Move stashbox package under pkg
* Remove StashBox from method names
* Add fingerprint conversion methods to Fingerprint

Refactor Fingerprints methods

* Make FindSceneByFingerprints accept fingerprints not scene ids
* Refactor SubmitSceneDraft to not require readers
* Have SubmitFingerprints accept scenes

Remove SceneReader dependency

* Move ScrapedScene to models package
* Move ScrapedImage into models package
* Move ScrapedGallery into models package
* Move Scene relationship matching out of stashbox package

This is now expected to be done in the client code

* Remove TagFinder dependency from stashbox.Client
* Make stashbox scene find full hierarchy of studios
* Move studio resolution into separate method
* Move studio matching out of stashbox package

This is now client code responsibility

* Move performer matching out of FindPerformerByID and FindPerformerByName
* Refactor performer querying logic and remove unused stashbox models

Renames FindStashBoxPerformersByPerformerNames to QueryPerformers and accepts names instead of performer ids

* Refactor SubmitPerformerDraft to not load relationships

This will be the responsibility of the calling code

* Remove repository references

pkg/sliceutil/collections.go

@@ -167,3 +167,13 @@ func ValuesToPtrs[T any](vs []T) []*T {
 	}
 	return ret
 }
+
+// Flatten returns a single slice containing all elements of the provided
+// slice of slices.
+func Flatten[T any](vs [][]T) []T {
+	var ret []T
+	for _, v := range vs {
+		ret = append(ret, v...)
+	}
+	return ret
+}