bazel: rename SkylarkValue

This change moves skylarkinterface.SkylarkValue to syntax.StarlarkValue,
and also skylarkinterface.SkylarkPrinter to syntax.Printer, where its
functionality is merged into the existing class of that name.

This change is entirely mechanical, except for syntax.Printer (naturally),
and MethodLibrary and SkylarkEvaluationTest, which needed a tweak
due the removal of the Printer.debugPrint static method.

All classes related to the representation of values are now in the evaluator package;
skylarkinterface now contains only the annotations.

This is a breaking change for copybara.

BEGIN_PUBLIC
bazel: rename SkylarkValue
END_PUBLIC
PiperOrigin-RevId: 282410278
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Starlark.java b/src/main/java/com/google/devtools/build/lib/syntax/Starlark.java
index 338bb6f..4623569 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Starlark.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Starlark.java
@@ -17,8 +17,6 @@
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkInterfaceUtils;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.util.Pair;
 import java.util.List;
 import java.util.Map;
@@ -45,7 +43,7 @@
   public static final Object UNBOUND = new UnboundMarker();
 
   @Immutable
-  private static final class UnboundMarker implements SkylarkValue {
+  private static final class UnboundMarker implements StarlarkValue {
     private UnboundMarker() {}
 
     @Override
@@ -59,7 +57,7 @@
     }
 
     @Override
-    public void repr(SkylarkPrinter printer) {
+    public void repr(Printer printer) {
       printer.append("<unbound>");
     }
   }
@@ -84,7 +82,7 @@
    * StarlarkValue.
    */
   public static boolean valid(Object x) {
-    return x instanceof SkylarkValue
+    return x instanceof StarlarkValue
         || x instanceof String
         || x instanceof Boolean
         || x instanceof Integer;
@@ -131,8 +129,8 @@
   public static boolean truth(Object x) {
     if (x instanceof Boolean) {
       return (Boolean) x;
-    } else if (x instanceof SkylarkValue) {
-      return ((SkylarkValue) x).truth();
+    } else if (x instanceof StarlarkValue) {
+      return ((StarlarkValue) x).truth();
     } else if (x instanceof String) {
       return !((String) x).isEmpty();
     } else if (x instanceof Integer) {