[NFC][RemoteInspection] Use existing cache to build conformance table

There is an existing cache which is built when looking up
FieldDescriptors. collectAllConformances ignored this cache and would
parse every FieldDescriptor again. Use the existing cache mechanism.

rdar://166098516
(cherry picked from commit 52c8b79)

Author: augusto2112

include/swift/RemoteInspection/TypeRefBuilder.h

@@ -597,6 +597,9 @@ class TypeRefBuilder {
     /// an external file.
     remote::ExternalTypeRefCache *ExternalTypeRefCache = nullptr;
 
+    /// Ensure all field descriptors are in the FieldTypeInfoCache.
+    void ensureAllFieldDescriptorsCached();
+
   public:
     ///
     /// Dumping typerefs, field declarations, builtin types, captures,
@@ -746,20 +749,18 @@ class TypeRefBuilder {
     ConformanceCollectionResult collectAllConformances() {
       ConformanceCollectionResult result;
 
-      // The Fields section has gathered info on types that includes their
-      // mangled names. Use that to build a dictionary from a type's demangled
-      // name to its mangled name
+      ensureAllFieldDescriptorsCached();
+
+      Demangler dem;
+      // Build the demangled to mangled name map from the FieldTypeInfoCache.
       std::unordered_map<std::string, std::string> typeNameToManglingMap;
-      for (const auto &section : ReflectionInfos) {
-        for (auto descriptor : section.Field) {
-          TypeRefBuilder::ScopedNodeFactoryCheckpoint checkpoint(&Builder);
-          auto TypeRef = readTypeRef(descriptor, descriptor->MangledTypeName);
-          auto OptionalMangledTypeName = normalizeReflectionName(TypeRef);
-          auto TypeName = nodeToString(Builder.demangleTypeRef(TypeRef));
-          if (OptionalMangledTypeName.has_value()) {
-            typeNameToManglingMap[TypeName] = OptionalMangledTypeName.value();
-          }
-        }
+      for (const auto &entry : FieldTypeInfoCache) {
+        const std::string &mangledName = entry.first;
+        RemoteRef<FieldDescriptor> descriptor = entry.second;
+
+        auto node = dem.demangleType(mangledName);
+        auto demangledName = nodeToString(node);
+        typeNameToManglingMap[demangledName] = mangledName;
       }
 
       // Collect all conformances and aggregate them per-conforming-type.

stdlib/public/RemoteInspection/TypeRefBuilder.cpp

@@ -335,6 +335,13 @@ void TypeRefBuilder::ReflectionTypeDescriptorFinder::
   ProcessedReflectionInfoIndexes.insert(Index);
 }
 
+void TypeRefBuilder::ReflectionTypeDescriptorFinder::
+    ensureAllFieldDescriptorsCached() {
+  for (size_t i = 0; i < ReflectionInfos.size(); ++i) {
+    populateFieldTypeInfoCacheWithReflectionAtIndex(i);
+  }
+}
+
 std::optional<RemoteRef<FieldDescriptor>>
 TypeRefBuilder::ReflectionTypeDescriptorFinder::findFieldDescriptorAtIndex(
     size_t Index, const std::string &MangledName) {