Make bulkPost and Post behavior align

Rather than having slightly different methods for the bulk and non-bulk move/copy behavior, the non-bulk version was so that the bulk version could call it and ingest the result.

Author: Mythicaeda

workspace-server/src/main/java/gov/nasa/jpl/aerie/workspace/server/FormattedError.java

@@ -194,6 +194,11 @@ public JsonObject toJson() {
     return builder.build();
   }
 
+  @Override
+  public String toString() {
+    return this.toJson().toString();
+  }
+
   /**
    * Internal class so that Javalin serializes the FormattedError class using its `toJson` method.
    * This avoids needing to call `toJson` every time the FormattedError class is used as an endpoint return.
@@ -206,7 +211,7 @@ public void serialize(
         final JsonGenerator jsonGenerator,
         final SerializerProvider serializerProvider) throws IOException
     {
-      jsonGenerator.writeRaw(formattedError.toJson().toString());
+      jsonGenerator.writeRaw(formattedError.toString());
     }
   }
 }