core/merge: Extract #doTrash() from #trashFileAsync()
core/merge: Extract #doTrash() from #trashFileAsync()

So #trashFolderAsync() stops logging both as trashed folder and
trashed file.

nono/cozy-desktop,nono/cozy-desktop,nono/cozy-desktop,nono/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop