bazel syntax: reverse syntax->events dependency

Details:
- Location has moved to syntax: it represents a location in a Starlark source file.
- StarlarkThread.makeDebugPrintHandler has moved to Event.
- The Eventable hack is gone.

This is a breaking API change for Copybara.

PiperOrigin-RevId: 304415517
diff --git a/src/main/java/com/google/devtools/build/lib/packages/TargetUtils.java b/src/main/java/com/google/devtools/build/lib/packages/TargetUtils.java
index 156d08e..302c856 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/TargetUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/TargetUtils.java
@@ -23,9 +23,9 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
 import com.google.devtools.build.lib.cmdline.Label;
-import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.syntax.Dict;
 import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.Location;
 import com.google.devtools.build.lib.util.Pair;
 import java.util.ArrayList;
 import java.util.Collection;