Run derive_classpath in VM

This allows us to get an accurate list of APEXes that contribute to
the classpaths, including staged APEXes. (Note that derive_classpath
itself is in an APEX, and we will run it from a staged APEX if
appropriate.)

Add com.android.sdkext (which contains derive_classpath) as an
explicit dependency; also fixed formatting while I was at it.

Remove the old initializeClasspaths method as it is now redudant.

Tweaked build.prop values to allow derive_classpath to run; more work
is needed though (b/189164487).

Bug: 200808307
Test: composd_cmd test-compile
Change-Id: Iae677274ebac1cdf721c5497c1d82eb22d2277db
diff --git a/compos/apk/assets/vm_config.json b/compos/apk/assets/vm_config.json
index d008c12..0e97228 100644
--- a/compos/apk/assets/vm_config.json
+++ b/compos/apk/assets/vm_config.json
@@ -18,7 +18,10 @@
       "name": "com.android.compos"
     },
     {
+      "name": "com.android.sdkext"
+    },
+    {
       "name": "{CLASSPATH}"
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/compos/apk/assets/vm_config_staged.json b/compos/apk/assets/vm_config_staged.json
index e42ebe0..5820982 100644
--- a/compos/apk/assets/vm_config_staged.json
+++ b/compos/apk/assets/vm_config_staged.json
@@ -19,7 +19,10 @@
       "name": "com.android.compos"
     },
     {
+      "name": "com.android.sdkext"
+    },
+    {
       "name": "{CLASSPATH}"
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/compos/apk/assets/vm_test_config.json b/compos/apk/assets/vm_test_config.json
index 9fd55b7..16d1037 100644
--- a/compos/apk/assets/vm_test_config.json
+++ b/compos/apk/assets/vm_test_config.json
@@ -1,21 +1,24 @@
 {
-    "version": 1,
-    "os": {
-        "name": "microdroid"
+  "version": 1,
+  "os": {
+    "name": "microdroid"
+  },
+  "task": {
+    "type": "executable",
+    "command": "/apex/com.android.compos/bin/compsvc"
+  },
+  "apexes": [
+    {
+      "name": "com.android.art"
     },
-    "task": {
-        "type": "executable",
-        "command": "/apex/com.android.compos/bin/compsvc"
+    {
+      "name": "com.android.compos"
     },
-    "apexes": [
-        {
-            "name": "com.android.art"
-        },
-        {
-            "name": "com.android.compos"
-        },
-        {
-            "name": "{CLASSPATH}"
-        }
-    ]
-}
\ No newline at end of file
+    {
+      "name": "com.android.sdkext"
+    },
+    {
+      "name": "{CLASSPATH}"
+    }
+  ]
+}