use tsweb debugger (#2420)

This PR switches the homegrown debug endpoint to using tsweb.Debugger, a neat toolkit with batteries included for pprof and friends, and making it easy to add additional debug info:

I've started out by adding a bunch of "introspect" endpoints
image

So users can see the acl, filter, config, derpmap and connected nodes as headscale sees them.

flake.nix

@@ -30,7 +30,7 @@
 
           # When updating go.mod or go.sum, a new sha will need to be calculated,
           # update this if you have a mismatch after doing a change to those files.
-          vendorHash = "sha256-ZQj2A0GdLhHc7JLW7qgpGBveXXNWg9ueSG47OZQQXEw=";
+          vendorHash = "sha256-CoxqEAxGdefyiIhz84LXXxPrZ1JWsX8Ernv1USr9JTs=";
 
           subPackages = ["cmd/headscale"];