wireguard: convert "table" to an interface option

Do the right thing, and use multiple interfaces for policy routing. For example, WireGuard interfaces do not allow multiple routes for the same CIDR range.

nixos/modules/services/networking/wireguard.nix

@@ -79,6 +79,16 @@ let
         description = "A list of commands called after shutting down the interface.";
       };
 
+      table = mkOption {
+        default = "main";
+        type = types.str;
+        description = ''The kernel routing table to add this interface's
+        associated routes to. Setting this is useful for e.g. policy routing
+        ("ip rule") or virtual routing and forwarding ("ip vrf"). Both numeric
+        table IDs and table names (/etc/rt_tables) can be used. Defaults to
+        "main".'';
+      };
+
       peers = mkOption {
         default = [];
         description = "Peers linked to the interface.";
@@ -160,14 +170,6 @@ let
         interval of 25 seconds; however, most users will not need this.'';
       };
 
-      table = mkOption {
-        default = "main";
-        type = types.str;
-        description = ''The kernel routing table to add this peer's associated
-        routes to. Setting this is useful for e.g. policy routing ("ip rule")
-        or virtual routing and forwarding ("ip vrf"). Both numeric table IDs
-        and table names (/etc/rt_tables) can be used. Defaults to "main".'';
-      };
     };
 
   };
@@ -217,7 +219,7 @@ let
 
             (map (peer:
             (map (allowedIP:
-            "${ipCommand} route replace ${allowedIP} dev ${name} table ${peer.table}"
+            "${ipCommand} route replace ${allowedIP} dev ${name} table ${values.table}"
             ) peer.allowedIPs)
             ) values.peers)