[IDE/SourceKit] New SourceKit request for filtered method list

`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

utils/gyb_sourcekit_support/UIDs.py

@@ -160,6 +160,8 @@ UID_KEYS = [
     KEY('CompileID', 'key.compileid'),
     KEY('CompilerArgsString', 'key.compilerargs-string'),
     KEY('ImplicitMembers', 'key.implicitmembers'),
+    KEY('ExpectedTypes', 'key.expectedtypes'),
+    KEY('Members', 'key.members'),
 ]
 
 
@@ -180,6 +182,7 @@ UID_REQUESTS = [
             'source.request.codecomplete.setpopularapi'),
     REQUEST('CodeCompleteSetCustom', 'source.request.codecomplete.setcustom'),
     REQUEST('TypeContextInfo', 'source.request.typecontextinfo'),
+    REQUEST('ConformingMethodList', 'source.request.conformingmethods'),
     REQUEST('CursorInfo', 'source.request.cursorinfo'),
     REQUEST('RangeInfo', 'source.request.rangeinfo'),
     REQUEST('RelatedIdents', 'source.request.relatedidents'),