This commit change the default behaviour and remove the notion of namespaces between the hosts. It allows all namespaces to be only filtered by the ACLs. This behavior is closer to tailsnet.

This call should be done quite at each modification of a server resources like RequestTags.
When a server changes it's tag we should rebuild the ACL rules.

When a server is added to headscale we also should update the ACLRules.

Rewrite some function to get rid of the dependency on Headscale object. This allows us
to write succinct test that are more easy to review and implement.

The improvements of the tests allowed to write the removal of the tagged hosts
from the namespace as specified here: https://tailscale.com/kb/1068/acl-tags/

This is a false positive on the way the function is built.
Small tests cases are all inside this functions, making it big.

Co-authored-by: Kristoffer Dalby <kradalby@kradalby.no>

Using h.ListAllMachines also listed the current machine in the result. It's unnecessary (I don't know if it's harmful).

Breaking the check with the `matchSourceAndDestinationWithRule` broke the tests. We have a specificity with the '*' destination that isn't symetrical.
I need to think of a better way to do this. It too hard to read.

This should fix the performance issue with computation of `dst` variable. It's also easier to read now.

added a simple filter to remove the current node

The dependency to the `headscale` struct makes tests harder to do.

This change allow to easily add some tests for this quite sensible function.

If aclPolicy is not defined, in updateAclPolicy, return an error.

Co-authored-by: Kristoffer Dalby <kradalby@kradalby.no>