Remove Unused Functions (#10516)

Remove Unused Functions (#10516)

* remove ReplaceLeft

* remove GetRepositoryByOwnerAndName chainload to models.GetRepositoryByOwnerAndName

* remove CheckUnitUser chainload to models.CheckUnitUser

* remove MakeAssigneeList

* remove DownloadDiff & DownloadPatch -> DownloadDiffOrPatch

* remove GetRandomBytesAsBase64

* remove PushUpdateDeleteTags

* remove GetUserByKeyID
(you still can resolve user by "k, err := GetPublicKeyByID; userID := k.OwnerID")

* remove BasicAuthEncode from struct package -> same function in modules/base/tools !

* remove UserID from api.utils

* remove unused func from structs package