🍒[6.1][cxx-interop] Avoid spurious type aliases in reverse interop

Explanation: Due to a missing check we emitted using declarations for
types we did not emit into the reverse interop header resulted in
compilation errors.
Scope: C++ reverse interop
Risk: Low. The fix is straightforward calling a function to do the check
if the entity should be included in the reverse interop header. It does
not affect other code paths.
Testing: Added compiler tests.
Issue: rdar://141688074
Reviewer: @egorzhdan

Original PR: #78287

Author: Gabor Horvath

lib/PrintAsClang/DeclAndTypePrinter.cpp

@@ -257,6 +257,9 @@ class DeclAndTypePrinter::Implementation
       for (const Decl *member : members) {
         if (member->getModuleContext()->isStdlibModule())
           break;
+        auto VD = dyn_cast<ValueDecl>(member);
+        if (!VD || !shouldInclude(VD))
+          continue;
         // TODO: support nested classes.
         if (isa<ClassDecl>(member))
           continue;

test/Interop/SwiftToCxx/structs/nested-structs-in-cxx.swift

@@ -60,3 +60,9 @@ public func makeRecordConfig() -> RecordConfig {
 public func makeAudioFileType() -> AudioFileType {
     return AudioFileType.CAF(AudioFileType.SubType(id: 42))
 }
+
+public class TestObject {
+    enum CustomError: Swift.Error {
+        case invalid
+    }
+}