testing: Add CA ID mappings to TKM tests

Extend the build-certs-chroot script is to fill in the public key
fingerprint of the CA certificate in the appropriate strongswan.con
files.

testing/tests/tkm/multiple-clients/hosts/sun/etc/strongswan.conf.in

@@ -5,4 +5,10 @@ charon-tkm {
     15 = 1
     16 = 2
   }
+  ca_mapping {
+    strongswan_ca {
+      id = 1
+      fingerprint = CA_SPK_HEX
+    }
+  }
 }