Load X509 keys from ziparchive

Add a function to parse the zip archive and load the certificate from
all the zip entries with the suffix "x509.pem".

Bug: 116655889
Test: unittests pass
Change-Id: I93bf7aef7462c0623e89fc2d466d7af2d3a758bc
diff --git a/Android.bp b/Android.bp
index 76e6985..c28dc3b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -201,6 +201,7 @@
         "libbase",
         "libcrypto",
         "libcrypto_utils",
+        "libziparchive",
     ],
 
     static_libs: [