Add assemble_cvd to com.android.virt

assemble_cvd directly or indirectly depends on these modules. To add
assemble_cvd to the com.anroid.virt APEX, these modules are marked as
being available to the APEX.

Bug: 174639526
Test: m com.android.virt
Change-Id: I6d68e275a3f7a73918bebf396b6fe732f206e1cf
diff --git a/Android.bp b/Android.bp
index 73a8f51..d207e70 100644
--- a/Android.bp
+++ b/Android.bp
@@ -230,6 +230,10 @@
             enabled: true,
         },
     },
+    apex_available: [
+        "//apex_available:platform",
+        "com.android.virt",
+    ],
 }
 
 // Compiler library for the host