Verify and mount extra apks

virtualizationservice currently passes extra apks and corresponding
idsigs as block devices. microdroid_manager will read the payload config
and mount the apks to /mnt/extra-apk/{index} after verifying them.

Bug: 205224817
Test: atest ComposHostTestCases MicrodroidHostTestCases
Test: manually edit vm config and see apks mounted
Change-Id: I9afa03cb7fabe0ca16b7926c4480d0b32c8bcd04
diff --git a/microdroid_manager/src/instance.rs b/microdroid_manager/src/instance.rs
index 8ba6f51..aadb71f 100644
--- a/microdroid_manager/src/instance.rs
+++ b/microdroid_manager/src/instance.rs
@@ -314,6 +314,7 @@
 #[derive(Debug, Serialize, Deserialize, PartialEq)]
 pub struct MicrodroidData {
     pub apk_data: ApkData,
+    pub extra_apks_data: Vec<ApkData>,
     pub apex_data: Vec<ApexData>,
     pub bootconfig: Box<[u8]>,
 }