feat: add casbin engine support

[kilosonc]

Signed-off-by: closetool [email protected]

Add casbin policy engine support

Fix: casbin/casbin#828

[kilosonc]

@hsluoyz @chrisohaver plz review

[chrisohaver]

Sorry - this had escaped my radar until now. Will review when I get a chance.

I will say though, that I have been considering breaking all policy engine plugins out into separate repositories, which would work better with Go modules.

[hsluoyz]

Hi @chrisohaver any update?

[chrisohaver]

Thanks for the ping. I have decided to reorganize the firewall plugin code, and split the policy engine plugins out into separate repositories. I'll try to get this done soon.