Reconcile network configuration

[mwindower]

reconcile network configuration with the information given in the firewall spec by the gardener-extension-provider-metal

[mwindower]

Successfully tested on a cluster in the test environment. With a release of the firewall-controller we could add this to the gepm.

[majst01]

LGTM but we do not have the possiblilty to record an event if networks changed. The whole changed logic is inside the Apply method, which does not return an indicator if changes where applied.
We will also create new frr configuration for very old frr versions which might be untested with this frr.conf.tpl.

[mwindower]

some notes here:

• changed the signature of the apply method of metal-networker
• record events about network reconcilation
• we check all flavors of FRR configurations we generate in combination with FRR 7.3 and 7.5 and Ubuntu+Debian - the check for FRR 7.2 is not sucessful (but only because of the machine template that uses a newer instruction ... but this is irrelevant for the firewall-controller)