Add preliminary spec11 monthly pipeline

This adds the scaffolding for a basic Spec11 pipeline- it gathers all domains from all time for a given project and counts how many there are. I've factored out a few common utilities for beam pipelines to avoid excessive duplication.

Future CLs will:
- Actually process domains via the SafeBrowsing API
- Generate a real spec11 report
- Template queries based on the input YearMonth
- Abstract more commonalities across beam pipelines to reduce boilerplate when adding new pipelines.

TESTED: FOSS test passed, and ran successfully on alpha

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=205997741

java/google/registry/beam/BeamUtils.java

@@ -0,0 +1,57 @@
+// Copyright 2018 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.beam;
+
+import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableList;
+import com.google.common.flogger.FluentLogger;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.beam.sdk.io.gcp.bigquery.SchemaAndRecord;
+
+/** Static utilities for {@code Beam} pipelines. */
+public class BeamUtils {
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+  /** Extracts a string representation of a field in a {@link GenericRecord}. */
+  public static String extractField(GenericRecord record, String fieldName) {
+    return String.valueOf(record.get(fieldName));
+  }
+
+  /**
+   * Checks that no expected fields in the record are missing.
+   *
+   * <p>Note that this simply makes sure the field is not null; it may still generate a parse error
+   * when interpreting the string representation of an object.
+   *
+   * @throws IllegalStateException if the record returns null for any field in {@code fieldNames}
+   */
+  public static void checkFieldsNotNull(
+      ImmutableList<String> fieldNames, SchemaAndRecord schemaAndRecord) {
+    GenericRecord record = schemaAndRecord.getRecord();
+    ImmutableList<String> nullFields =
+        fieldNames
+            .stream()
+            .filter(fieldName -> record.get(fieldName) == null)
+            .collect(ImmutableList.toImmutableList());
+    String missingFieldList = Joiner.on(", ").join(nullFields);
+    if (!nullFields.isEmpty()) {
+      throw new IllegalStateException(
+          String.format(
+              "Read unexpected null value for field(s) %s for record %s",
+              missingFieldList, record));
+    }
+  }
+}