network: Introduce MACsec

Media Access Control Security (MACsec) is an 802.1AE IEEE
industry-standard security technology that provides secure
communication for all traffic on Ethernet links.
MACsec provides point-to-point security on Ethernet links between
directly connected nodes and is capable of identifying and preventing
most security threats, including denial of service, intrusion,
man-in-the-middle, masquerading, passive wiretapping, and playback attacks.

Closes #5754

test/fuzz/fuzz-netdev-parser/directives.netdev

@@ -174,3 +174,19 @@ SessionId=
 PeerSessionId=
 Layer2SpecificHeader=
 Name=
+[MACSEC]
+Port=
+Encrypt=
+[MACsecReceiveAssociation]
+Port=
+MACAddress=
+PacketNumber=
+KeyId=
+Key=
+[MACsecReceiveChannel]
+Port=
+MACAddress=
+[MACsecTransmitAssociation]
+PacketNumber=
+KeyId=
+Key=