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/composd/src/instance_starter.rs b/compos/composd/src/instance_starter.rs
index 729e5b6..6946c11 100644
--- a/compos/composd/src/instance_starter.rs
+++ b/compos/composd/src/instance_starter.rs
@@ -29,7 +29,6 @@
     COMPOS_DATA_ROOT, IDSIG_FILE, INSTANCE_IMAGE_FILE, PRIVATE_KEY_BLOB_FILE, PUBLIC_KEY_FILE,
 };
 use log::{info, warn};
-use std::env;
 use std::fs;
 use std::path::{Path, PathBuf};
 
@@ -111,8 +110,7 @@
         // If we get this far then the instance image is valid in the current context (e.g. the
         // current set of APEXes) and the key blob can be successfully decrypted by the VM. So the
         // files have not been tampered with and we're good to go.
-
-        Self::initialize_service(service, &key_blob)?;
+        service.initializeSigningKey(&key_blob).context("Loading signing key")?;
 
         Ok(compos_instance)
     }
@@ -145,28 +143,11 @@
 
         // Unlike when starting an existing instance, we don't need to verify the key, since we
         // just generated it and have it in memory.
-
-        Self::initialize_service(service, &key_data.keyBlob)?;
+        service.initializeSigningKey(&key_data.keyBlob).context("Loading signing key")?;
 
         Ok(compos_instance)
     }
 
-    fn initialize_service(service: &Strong<dyn ICompOsService>, key_blob: &[u8]) -> Result<()> {
-        // Key blob is assumed to be verified/trusted.
-        service.initializeSigningKey(key_blob).context("Loading signing key")?;
-
-        // TODO(198211396): Implement correctly.
-        service
-            .initializeClasspaths(
-                &env::var("BOOTCLASSPATH")?,
-                &env::var("DEX2OATBOOTCLASSPATH")?,
-                &env::var("SYSTEMSERVERCLASSPATH")?,
-                &env::var("STANDALONE_SYSTEMSERVER_JARS")?,
-            )
-            .context("Initializing *CLASSPATH")?;
-        Ok(())
-    }
-
     fn start_vm(
         &self,
         virtualization_service: &dyn IVirtualizationService,