`source.request.conformingmethods` is a new SourceKit request which
receives a source position and a list of protocol namses, returns a list
of methods whose return type conforms to the requested protocols.
rdar://problem/44699573
This is a new SourceKit request which receives a position in the source
file, returns possible expected types and their members which can be
referenced by "implicit member expression" syntax.
Currently, SourceKit's CMake functions all use DEPENDS to specify
libraries the targets will link with. This is confusing as it doesn't
behave the same way that add_swift behaves, and implies that
dependencies are created when there aren't.
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.
