Add soong support for resource shrinking

This adds a new flag to the optimize section to allow invoking the resource shrinker

Bug: 246217952
Test: m
Change-Id: I2e7851af1189db2a6adf6f9f9f444a1d7f3a8d60
diff --git a/java/dex.go b/java/dex.go
index a44d792..f5969a5 100644
--- a/java/dex.go
+++ b/java/dex.go
@@ -63,6 +63,8 @@
 		// classes referenced by the app manifest.  Defaults to false.
 		No_aapt_flags *bool
 
+		Shrink_resources *bool
+
 		// Flags to pass to proguard.
 		Proguard_flags []string