Add BuildEventProtocolOptions; use to enable/disable important_outputs

The important_outputs field is deprecated, and this adds a flag to disable
its generation entirely.

PiperOrigin-RevId: 197186530
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/TargetCompleteEvent.java b/src/main/java/com/google/devtools/build/lib/analysis/TargetCompleteEvent.java
index e6f5c3f..a359446 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/TargetCompleteEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/TargetCompleteEvent.java
@@ -232,10 +232,12 @@
 
     // TODO(aehlig): remove direct reporting of artifacts as soon as clients no longer
     // need it.
-    addImportantOutputs(builder, converters, getLegacyFilteredImportantArtifacts());
-    if (baselineCoverageArtifacts != null) {
-      addImportantOutputs(
-          builder, (artifact -> BASELINE_COVERAGE), converters, baselineCoverageArtifacts);
+    if (converters.getOptions().legacyImportantOutputs) {
+      addImportantOutputs(builder, converters, getLegacyFilteredImportantArtifacts());
+      if (baselineCoverageArtifacts != null) {
+        addImportantOutputs(
+            builder, (artifact -> BASELINE_COVERAGE), converters, baselineCoverageArtifacts);
+      }
     }
 
     BuildEventStreamProtos.TargetComplete complete = builder.build();