add OutputGroupProvider.DEFAULT_GROUPS for commonly built groups

unit tests and main code have fallen out of sync a few times, so
consolidating the defaults here to make mistakes harder later on.
one could argue this also gives a little better mental locality.

--
MOS_MIGRATED_REVID=88921641
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupProvider.java b/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupProvider.java
index a0c4f78..90b373f 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupProvider.java
@@ -15,6 +15,7 @@
 package com.google.devtools.build.lib.analysis;
 
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
@@ -84,6 +85,12 @@
    */
   public static final String DEFAULT = "default";
 
+  /**
+   * The default set of OutputGroups we typically want to build.
+   */
+  public static final ImmutableSet<String> DEFAULT_GROUPS =
+      ImmutableSet.of(DEFAULT, TEMP_FILES, HIDDEN_TOP_LEVEL);
+
   private final ImmutableMap<String, NestedSet<Artifact>> outputGroups;
 
   OutputGroupProvider(ImmutableMap<String, NestedSet<Artifact>> outputGroups) {