testing: Rename public keys in DNSSEC scenarios

We will generate PEM-encoded public keys with the script.

testing/tests/ikev2/net2net-dnssec/hosts/moon/etc/ipsec.conf

@@ -14,7 +14,7 @@ conn net-net
 	left=PH_IP_MOON
 	leftid=moon.strongswan.org
 	leftsubnet=10.1.0.0/16
-	leftsigkey=moonPub.der
+	leftsigkey=moonPub.pem
 	leftauth=pubkey
 	leftfirewall=yes
 	right=sun.strongswan.org

testing/tests/ikev2/net2net-dnssec/hosts/sun/etc/ipsec.conf

@@ -14,7 +14,7 @@ conn net-net
 	left=PH_IP_SUN
 	leftid=sun.strongswan.org
 	leftsubnet=10.2.0.0/16
-	leftsigkey=sunPub.der
+	leftsigkey=sunPub.pem
 	leftauth=pubkey
 	leftfirewall=yes
 	right=moon.strongswan.org

testing/tests/ikev2/rw-dnssec/hosts/moon/etc/ipsec.conf

@@ -14,7 +14,7 @@ conn rw
 	leftsubnet=10.1.0.0/16
 	leftid=moon.strongswan.org
 	leftauth=pubkey
-	leftsigkey=moonPub.der
+	leftsigkey=moonPub.pem
 	leftfirewall=yes
 	right=%any
 	rightauth=pubkey

testing/tests/swanctl/rw-dnssec/hosts/carol/etc/swanctl/swanctl.conf

@@ -8,7 +8,7 @@ connections {
       local {
          auth = pubkey
          id = carol.strongswan.org
-         pubkeys = carolPub.der
+         pubkeys = carolPub.pem
       }
       remote {
          auth = pubkey

testing/tests/swanctl/rw-dnssec/hosts/dave/etc/swanctl/swanctl.conf

@@ -8,7 +8,7 @@ connections {
       local {
          auth = pubkey
          id = dave.strongswan.org
-         pubkeys = davePub.der
+         pubkeys = davePub.pem
       }
       remote {
          auth = pubkey

testing/tests/swanctl/rw-dnssec/hosts/moon/etc/swanctl/swanctl.conf

@@ -7,7 +7,7 @@ connections {
       local {
          auth = pubkey
          id = moon.strongswan.org
-         pubkeys = moonPub.der
+         pubkeys = moonPub.pem
       }
       remote {
          auth = pubkey