lib.query2 organizational cleanup

This just changes

query2/

to

query2/   # Code common to query, cquery, aquery
  aquery/ # aquery-specific code
  query/  # query-specific code
  cquery/ # cquery-specific code

Lots of files reference each other so it's a huge change, but conceptually shallow.

This isn't perfect. Some classes probably aren't in the right place. Some should probably be refactored into their command-specific vs. generic parts. And it'd be nice to separate cquery, query, and aquery into independent BUILD libraries. But BUILD refactoring makes this 10x worse and as-is I think this makes navigation easier.

PiperOrigin-RevId: 247015827
diff --git a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
index 5c168958..f3f153b 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/SkyQueryEnvironment.java
@@ -83,6 +83,7 @@
 import com.google.devtools.build.lib.query2.engine.StreamableQueryEnvironment;
 import com.google.devtools.build.lib.query2.engine.ThreadSafeOutputFormatterCallback;
 import com.google.devtools.build.lib.query2.engine.Uniquifier;
+import com.google.devtools.build.lib.query2.query.BlazeTargetAccessor;
 import com.google.devtools.build.lib.skyframe.BlacklistedPackagePrefixesValue;
 import com.google.devtools.build.lib.skyframe.ContainingPackageLookupFunction;
 import com.google.devtools.build.lib.skyframe.GraphBackedRecursivePackageProvider;
@@ -135,7 +136,7 @@
   // 10k is likely a good balance between using batch efficiently and not blowing up memory.
   // TODO(janakr): Unify with RecursivePackageProviderBackedTargetPatternResolver's constant.
   protected static final int BATCH_CALLBACK_SIZE = 10000;
-  protected static final int DEFAULT_THREAD_COUNT = Runtime.getRuntime().availableProcessors();
+  public static final int DEFAULT_THREAD_COUNT = Runtime.getRuntime().availableProcessors();
   private static final int MAX_QUERY_EXPRESSION_LOG_CHARS = 1000;
   private static final Logger logger = Logger.getLogger(SkyQueryEnvironment.class.getName());