apkverify: Migrate from ring to openssl crate

Switch to using the certified implementation of cryptographic
algorithms, boringssl, that's available through the openssl crate.

Add an ECDSA signed APK to the test suite to give that algorithm some
coverage.

Bug: 232676161
Test: atest libapkverify.test
Test: atest libapkverify.integration_test
Change-Id: I5f86b40e110d8aaeb22109757253950bd7824833
diff --git a/libs/apkverify/Android.bp b/libs/apkverify/Android.bp
index df1cac6..4c0e1f8 100644
--- a/libs/apkverify/Android.bp
+++ b/libs/apkverify/Android.bp
@@ -13,7 +13,7 @@
         "libbyteorder",
         "libbytes",
         "liblog_rust",
-        "libring",
+        "libopenssl",
         "libx509_parser",
         "libzip",
     ],