Add FlowMetadata (containing isSuperuser) to custom flow logic

This also bypasses signed mark validation during domain creation if
the flow is being executed as superuser.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=145435268

java/google/registry/flows/FlowMetadata.java

@@ -0,0 +1,38 @@
+// Copyright 2016 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.flows;
+
+import com.google.auto.value.AutoValue;
+import google.registry.model.ImmutableObject;
+
+/** Object to hold metadata specific to a particular execution of a flow. */
+@AutoValue
+public abstract class FlowMetadata extends ImmutableObject {
+
+  public abstract boolean isSuperuser();
+
+  public static Builder newBuilder() {
+    return new AutoValue_FlowMetadata.Builder();
+  }
+
+  /** Builder for {@link FlowMetadata} */
+  @AutoValue.Builder
+  public abstract static class Builder {
+
+    public abstract Builder setSuperuser(boolean isSuperuser);
+
+    public abstract FlowMetadata build();
+  }
+}