bazel: pass SkylarkType not Class to Depset.of where convenient

This CL addresses Artifact, Label, and String.
A few ad-hoc classes remain.

PiperOrigin-RevId: 282013214
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupInfo.java b/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupInfo.java
index aa90fac..ac99a11 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupInfo.java
@@ -248,7 +248,7 @@
 
     NestedSet<Artifact> result = outputGroups.get(key);
     if (result != null) {
-      return Depset.of(Artifact.class, result);
+      return Depset.of(Artifact.TYPE, result);
     } else {
       throw new EvalException(loc, String.format(
           "Output group %s not present", key
@@ -272,7 +272,7 @@
     if (result == null) {
       return null;
     }
-    return Depset.of(Artifact.class, result);
+    return Depset.of(Artifact.TYPE, result);
   }
 
   @Override