Consolidate type providers into two: one for legacy and one for modern

PiperOrigin-RevId: 690350923

Author: jcking

common/BUILD

@@ -653,11 +653,9 @@ cc_library(
         "//extensions/protobuf/internal:map_reflection",
         "//extensions/protobuf/internal:qualify",
         "//internal:casts",
-        "//internal:deserialize",
         "//internal:json",
         "//internal:message_equality",
         "//internal:number",
-        "//internal:overflow",
         "//internal:protobuf_runtime_version",
         "//internal:serialize",
         "//internal:status_macros",

common/json.h

@@ -495,9 +495,7 @@ class AnyToJsonConverter {
     return nullptr;
   }
 
-  virtual absl::Nullable<google::protobuf::MessageFactory*> message_factory() const {
-    return nullptr;
-  }
+  virtual absl::Nullable<google::protobuf::MessageFactory*> message_factory() const = 0;
 };
 
 inline std::pair<absl::Nonnull<const google::protobuf::DescriptorPool*>,