Firewall: Rules - add state-policy property

[AdSchellevis]

Important notices

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• I have read the contributing guide lines at https://github.com/opnsense/core/blob/master/CONTRIBUTING.md
• I am convinced that my issue is new after having checked both open and closed issues at https://github.com/opnsense/core/issues?q=is%3Aissue

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

In some cases it can be practical to be able to choose how states are bound on a more granular level. The advanced property "Bind states to interface" offers a way to always bind states to an interface or leave them floating.

Describe the solution you like

Add the property state-policy option.

Describe alternatives you considered

none

Additional context

• https://man.freebsd.org/cgi/man.cgi?pf.conf(5)#OPTIONS