tests: add a couple of files containing all the sections and directives

This should help the fuzzers to discover code paths faster.

In case anyone is interested, they were generated with the following script
```
perl -aF'/[\s,]+/' -ne '
if (my ($s, $d) = ($F[0] =~ /^([^\s\.]+)\.([^\s\.]+)$/)) { $d{$s}{$d} = 1; }
END { while (my ($key, $value) = each %d) {
    printf "[%s]\n%s\n", $key, join("\n", keys(%$value))
}}'
```
by passing src/network/networkd-network-gperf.gperf and
src/network/netdev/netdev-gperf.gperf to it.

1 files changed, 153 insertions, 0 deletions

diff --git a/test/fuzz/fuzz-netdev-parser/directives.netdev b/test/fuzz/fuzz-netdev-parser/directives.netdev
new file mode 100644
index 0000000000..4725d2dad4
--- /dev/null
+++ b/test/fuzz/fuzz-netdev-parser/directives.netdev
@@ -0,0 +1,153 @@
+[VLAN]
+MVRP=
+LooseBinding=
+ReorderHeader=
+Id=
+GVRP=
+[MACVLAN]
+Mode=
+[WireGuard]
+ListenPort=
+PrivateKey=
+FwMark=
+[MACVTAP]
+Mode=
+[Match]
+Architecture=
+Host=
+KernelVersion=
+Virtualization=
+KernelCommandLine=
+[GENEVE]
+DestinationPort=
+TTL=
+UDP6ZeroCheckSumTx=
+TOS=
+Id=
+UDPChecksum=
+UDP6ZeroChecksumTx=
+FlowLabel=
+UDP6ZeroChecksumRx=
+Remote=
+UDP6ZeroCheckSumRx=
+[Bridge]
+ForwardDelaySec=
+HelloTimeSec=
+MaxAgeSec=
+STP=
+MulticastSnooping=
+DefaultPVID=
+MulticastQuerier=
+AgeingTimeSec=
+Priority=
+GroupForwardMask=
+VLANFiltering=
+[VRF]
+TableId=
+Table=
+[Peer]
+MACAddress=
+Name=
+[WireGuardPeer]
+Endpoint=
+PresharedKey=
+PersistentKeepalive=
+PublicKey=
+AllowedIPs=
+[Tunnel]
+FooOverUDP=
+IPv6FlowLabel=
+Remote=
+AllowLocalRemote=
+Local=
+TOS=
+Independent=
+Key=
+InputKey=
+Encapsulation=
+Mode=
+OutputKey=
+DiscoverPathMTU=
+FOUDestinationPort=
+CopyDSCP=
+EncapsulationLimit=
+TTL=
+FOUSourcePort=
+[VXLAN]
+UDP6ZeroChecksumRx=
+ARPProxy=
+FlowLabel=
+Local=
+RemoteChecksumTx=
+RouteShortCircuit=
+Remote=
+L3MissNotification=
+Group=
+FDBAgeingSec=
+MacLearning=
+Id=
+RemoteChecksumRx=
+TOS=
+L2MissNotification=
+UDP6ZeroChecksumTx=
+UDP6ZeroCheckSumRx=
+UDPCheckSum=
+GroupPolicyExtension=
+MaximumFDBEntries=
+TTL=
+DestinationPort=
+ReduceARPProxy=
+PortRange=
+UDPChecksum=
+UDP6ZeroCheckSumTx=
+[VXCAN]
+Peer=
+[Bond]
+LearnPacketIntervalSec=
+TransmitHashPolicy=
+MIIMonitorSec=
+PacketsPerSlave=
+DownDelaySec=
+PrimaryReselectPolicy=
+ResendIGMP=
+ARPAllTargets=
+AdActorSystemPriority=
+UpDelaySec=
+AdSelect=
+AdActorSystem=
+AdUserPortKey=
+FailOverMACPolicy=
+ARPValidate=
+Mode=
+GratuitousARP=
+ARPIPTargets=
+MinLinks=
+LACPTransmitRate=
+ARPIntervalSec=
+AllSlavesActive=
+[FooOverUDP]
+Protocol=
+Port=
+Encapsulation=
+[Tap]
+MultiQueue=
+OneQueue=
+User=
+Group=
+PacketInfo=
+VNetHeader=
+[IPVLAN]
+Mode=
+Flags=
+[Tun]
+OneQueue=
+MultiQueue=
+PacketInfo=
+Group=
+User=
+[NetDev]
+Kind=
+MACAddress=
+MTUBytes=
+Description=
+Name=