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/analysis/RuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
index 141c310..88bd547 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
@@ -65,7 +65,6 @@
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.ExtendedEventHandler.Postable;
-import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.Aspect;
 import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
@@ -95,6 +94,7 @@
 import com.google.devtools.build.lib.packages.Type.LabelClass;
 import com.google.devtools.build.lib.skyframe.ConfiguredTargetAndData;
 import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.Location;
 import com.google.devtools.build.lib.syntax.StarlarkSemantics;
 import com.google.devtools.build.lib.util.FileTypeSet;
 import com.google.devtools.build.lib.util.OS;