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

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

javatests/google/registry/beam/BeamUtilsTest.java

@@ -0,0 +1,86 @@
+// 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 static com.google.common.truth.Truth.assertThat;
+import static google.registry.testing.JUnitBackports.assertThrows;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.avro.Schema;
+import org.apache.avro.generic.GenericData;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.beam.sdk.io.gcp.bigquery.SchemaAndRecord;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link BeamUtils} */
+@RunWith(JUnit4.class)
+public class BeamUtilsTest {
+
+  private static final String GENERIC_SCHEMA =
+      "{\"name\": \"AnObject\", "
+          + "\"type\": \"record\", "
+          + "\"fields\": ["
+          + "{\"name\": \"aString\", \"type\": \"string\"},"
+          + "{\"name\": \"aFloat\", \"type\": \"float\"}"
+          + "]}";
+
+  private SchemaAndRecord schemaAndRecord;
+
+  @Before
+  public void initializeRecord() {
+    // Create a record with a given JSON schema.
+    GenericRecord record = new GenericData.Record(new Schema.Parser().parse(GENERIC_SCHEMA));
+    record.put("aString", "hello world");
+    record.put("aFloat", 2.54);
+    schemaAndRecord = new SchemaAndRecord(record, null);
+  }
+
+  @Test
+  public void testExtractField_fieldExists_returnsExpectedStringValues() {
+    assertThat(BeamUtils.extractField(schemaAndRecord.getRecord(), "aString"))
+        .isEqualTo("hello world");
+    assertThat(BeamUtils.extractField(schemaAndRecord.getRecord(), "aFloat")).isEqualTo("2.54");
+  }
+
+  @Test
+  public void testExtractField_fieldDoesntExist_returnsNull() {
+    schemaAndRecord.getRecord().put("aFloat", null);
+    assertThat(BeamUtils.extractField(schemaAndRecord.getRecord(), "aFloat")).isEqualTo("null");
+    assertThat(BeamUtils.extractField(schemaAndRecord.getRecord(), "missing")).isEqualTo("null");
+  }
+
+  @Test
+  public void testCheckFieldsNotNull_noExceptionIfAllPresent() {
+    BeamUtils.checkFieldsNotNull(ImmutableList.of("aString", "aFloat"), schemaAndRecord);
+  }
+
+  @Test
+  public void testCheckFieldsNotNull_fieldMissing_throwsException() {
+    IllegalStateException expected =
+        assertThrows(
+            IllegalStateException.class,
+            () ->
+                BeamUtils.checkFieldsNotNull(
+                    ImmutableList.of("aString", "aFloat", "notAField"), schemaAndRecord));
+    assertThat(expected)
+        .hasMessageThat()
+        .isEqualTo(
+            "Read unexpected null value for field(s) notAField for record "
+                + "{\"aString\": \"hello world\", \"aFloat\": 2.54}");
+  }
+}