KVM: add configurable MAC/IP script hook for static ARP/NDP and routes

[wido]

Introduces a new agent.properties option vm.network.macip.script (absolute path, disabled by default) that BridgeVifDriver invokes on every NIC plug (VM start) and unplug (VM stop).

This is very useful in EVPN+VXLAN environments as it can reduce BUM traffic. By setting static ARP/NDP entries bridges can be configured using 'neigh_suppress on' as the ARP/NDP entries are already set statically by CloudStack.

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 18.94%. Comparing base (348ce95) to head (492211c).
⚠️ Report is 240 commits behind head on main.

Files with missing lines	Patch %	Lines
...cloud/hypervisor/kvm/resource/BridgeVifDriver.java	23.80%	14 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #13495      +/-   ##
============================================
+ Coverage     17.68%   18.94%   +1.26%     
- Complexity    15793    18373    +2580     
============================================
  Files          5922     6192     +270     
  Lines        533123   556572   +23449     
  Branches      65201    67958    +2757     
============================================
+ Hits          94268   105449   +11181     
- Misses       428212   439542   +11330     
- Partials      10643    11581     +938     

Flag	Coverage Δ
uitests	3.51% <ø> (-0.18%)	⬇️
unittests	20.15% <33.33%> (+1.39%)	⬆️

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[DaanHoogland]

clgtm, why not set your script as default value for the property @wido ? (if it is well tested and robust, that is)

[wido]

clgtm, why not set your script as default value for the property @wido ? (if it is well tested and robust, that is)

Thanks, the reason the script does not always execute is that it could break existing setups. Therefor it is not set by default.

[DaanHoogland]

clgtm, why not set your script as default value for the property @wido ? (if it is well tested and robust, that is)

Thanks, the reason the script does not always execute is that it could break existing setups. Therefor it is not set by default.

yeah, that is what I meant by robust ;) np, fine like this as well.