Microdroid activates host APEXes

Host apexes are passed to microdroid via the payload composite image.
The payload composite image can be created by either
mk_payload_signature/mk_cdisk or mk_payload.

For now, microdroid expects two APEXes from the host:
- com.android.adbd
- com.android.sdkext

The exact set of host apexes for microdroid is TBD. The current set is
only for demonstration.

Bug: 181093750
Test: MicrodroidTestCase
Change-Id: I7fe33fe03ac94799a4e109b83286bfb39e44b882
diff --git a/apex/Android.bp b/apex/Android.bp
index 9c201b4..8af22ff 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -44,15 +44,19 @@
     },
     binaries: [
         "fd_server",
-        "mk_cdisk",
-        "mk_microdroid_signature",
         "virtmanager",
         "vm",
+
+        // tools to create composite images
+        "mk_cdisk",
+        "mk_microdroid_signature",
+        "mk_payload",
     ],
     prebuilts: [
         "com.android.virt.init.rc",
         "microdroid_cdisk.json",
         "microdroid_cdisk_env.json",
+        "microdroid_payload.json",
         "microdroid_uboot_env",
         "microdroid_bootloader",
     ],