Option to put static-dhcp mapped clients into alias.

[pcarinhas]

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Is your feature request related to a problem? Please describe.

For many static dhcp reservations, having the option to put that client into an alias by default, or a specific alias
would allow efficient way to deal with client rules. Especially so for clients that are for example non-routable or
specialized clients.

Describe the solution you like

Have an option in the DHCP : Static Mappings Client area, that allows you to put the client into
one of the existing alias groups, and allows there to be a default (in the DHCP general area) value of "static_map" or similar.

Describe alternatives you considered

Alternatives could be a similar feature to put DHCP static maps into a VLAN, but this would be more complex.
One could then deal with VLAN rules to control such clients.

Additional context

The alias feature of opnSense is very powerful and useful to simplify firewall rules.
Certain clients like (phones, IoT) need special handling in the rules. The workflow of

a. adding static client
b. adding client to alias

can be a PITA, especially if you have to create many clients. So having them be put into an alias at the start
is very helpful, and I think a good feature to have.
This solution is useful for both a closed-exception or an open-exception style of firewall setup.