Align parameter formats for zone data commands

Seems silly that one command uses --tlds for the required parameter, while the other one doesn't.

As part of this change, create a DateParameter for commands that require only a date (i.e. a DateTime parameter restricted to midnight UTC).

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148106721

java/google/registry/tools/params/DateParameter.java

@@ -0,0 +1,45 @@
+// Copyright 2017 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.tools.params;
+
+import static org.joda.time.DateTimeZone.UTC;
+
+import org.joda.time.DateTime;
+import org.joda.time.DateTimeZone;
+import org.joda.time.format.DateTimeFormatter;
+import org.joda.time.format.ISODateTimeFormat;
+
+/**
+ * {@link DateTime} CLI parameter converter/validator restricted to dates. The {@link DateTime}s
+ * produced by this class will always have a time zone of {@link DateTimeZone#UTC}.
+ */
+public final class DateParameter extends ParameterConverterValidator<DateTime> {
+
+  public DateParameter() {
+    super("not an ISO-8601 date");
+  }
+
+  /**
+   * Parser for DateTimes that permits only a restricted subset of ISO 8601 datetime syntax.
+   * The supported format is "YYYY-MM-DD", i.e. there must only be a complete date.
+   */
+  private static final DateTimeFormatter STRICT_DATE_PARSER =
+      new DateTimeFormatter(null, ISODateTimeFormat.date().getParser());
+
+  @Override
+  public DateTime convert(String value) {
+    return DateTime.parse(value, STRICT_DATE_PARSER).withZoneRetainFields(UTC);
+  }
+}