FindNotes failure when a linked notebook is no longer available

[mpnow]

I think this may be similar to what was fixed for ListNotebooks in #45.

In ENSession.m > findNotes_nextFindInLinkedScopeWithContext, if the linked notebook is for some reason no longer available to the user, then I believe the call to findNotesMetadataWithFilter will fail with an EDAMNotFoundException.

[everic]

This should no longer happen. FindNotes will only use ENNotebooks found with listNotebooks, and if a sharedNotebook record is gone, the linked notebook is not listed in the notebook list, so when we're searching notes, the notebook is not going to be searched. I've verified this case with the latest code.