Support asset_dirs property in bp2build for android_{app,library}

Bug: 276928228
Test: Unit Tests
Change-Id: I6a2899de21e046e54cd0cd71314bf7aec4a470f6
diff --git a/java/app.go b/java/app.go
index e277aed..1d1ea97 100755
--- a/java/app.go
+++ b/java/app.go
@@ -1628,8 +1628,10 @@
 	deps := depLabels.Deps
 	deps.Append(depLabels.StaticDeps)
 
-	aapt := a.convertAaptAttrsWithBp2Build(ctx)
-
+	aapt, supported := a.convertAaptAttrsWithBp2Build(ctx)
+	if !supported {
+		return
+	}
 	certificate, certificateName := android.BazelStringOrLabelFromProp(ctx, a.overridableAppProperties.Certificate)
 
 	manifestValues := &manifestValueAttribute{}