fix auto approver on register and new policy (#2506)

* fix issue auto approve route on register bug

This commit fixes an issue where routes where not approved
on a node during registration. This cause the auto approval
to require the node to readvertise the routes.

Fixes #2497
Fixes #2485

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* hsic: only set db policy if exist

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* policy: calculate changed based on policy and filter

v1 is a bit simpler than v2, it does not pre calculate the auto approver map
and we cannot tell if it is changed.

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

---------

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/grpcv1.go

@@ -739,6 +739,11 @@ func (api headscaleV1APIServer) SetPolicy(
 
 	// Only send update if the packet filter has changed.
 	if changed {
+		err = api.h.autoApproveNodes()
+		if err != nil {
+			return nil, err
+		}
+
 		ctx := types.NotifyCtx(context.Background(), "acl-update", "na")
 		api.h.nodeNotifier.NotifyAll(ctx, types.UpdateFull())
 	}