* InterfaceGen reports a primary associated type as a reference to the
'associatedtype' declaration
* CursorInfo on a primary associated type returns information of the
'associatedtype' declaration
rdar://93275458
Right now 'fileprivate' is parsed as an alias for 'private' (or
perhaps vice versa, since the semantics of 'private' haven't changed
yet). This allows us to migrate code to 'fileprivate' without waiting
for the full implementation.
The code goes into its own sub-tree under 'tools' but tests go under 'test',
so that running 'check-swift' will also run all the SourceKit tests.
SourceKit is disabled on non-darwin platforms.
