[Completion] Only provide macro completions when they are valid

Only return macros that are valid in their current position, ie. an
attached macro is not valid on a nominal.

Also return freestanding expression macros in code block item position
and handle the new freestanding code item macros.

Resolves rdar://105563583.

tools/SourceKit/lib/SwiftLang/CodeCompletionOrganizer.cpp

@@ -1167,9 +1167,9 @@ Completion *CompletionBuilder::finish() {
         new (sink.allocator) ContextFreeCodeCompletionResult(
             contextFreeBase.getKind(),
             contextFreeBase.getOpaqueAssociatedKind(), opKind,
-            contextFreeBase.isSystem(), contextFreeBase.isAsync(),
-            contextFreeBase.hasAsyncAlternative(), newCompletionString,
-            contextFreeBase.getModuleName(),
+            contextFreeBase.getMacroRoles(), contextFreeBase.isSystem(),
+            contextFreeBase.isAsync(), contextFreeBase.hasAsyncAlternative(),
+            newCompletionString, contextFreeBase.getModuleName(),
             contextFreeBase.getBriefDocComment(),
             contextFreeBase.getAssociatedUSRs(),
             contextFreeBase.getResultType(),