Use the vm tool

MicrodroidHostTestCases now uses the vm tool to create the VM. It no
longer directly interacts with crosvm and mk_cdisk.

The READMD.md file is rewritten to fully reflect the recent changes, and
also to add description about building an app for microdroid.

Bug: 185891097
Test: atest MicrodroidHostTestCases
Change-Id: I5fdc854390fd362ebead22a4a36af75c30500a81
diff --git a/microdroid/Android.bp b/microdroid/Android.bp
index 41ee0d2..6424988 100644
--- a/microdroid/Android.bp
+++ b/microdroid/Android.bp
@@ -391,13 +391,8 @@
 }
 
 prebuilt_etc {
-    name: "microdroid_cdisk.json",
-    src: "microdroid_cdisk.json",
-}
-
-prebuilt_etc {
-    name: "microdroid_cdisk_env.json",
-    src: "microdroid_cdisk_env.json",
+    name: "microdroid.json",
+    src: "microdroid.json",
 }
 
 prebuilt_etc {