radicale: Add extraArgs option to assist in data migration

nixos/modules/services/networking/radicale.nix

@@ -48,6 +48,12 @@ in
         configuration file.
       '';
     };
+
+    services.radicale.extraArgs = mkOption {
+      type = types.listOf types.string;
+      default = [];
+      description = "Extra arguments passed to the Radicale daemon.";
+    };
   };
 
   config = mkIf cfg.enable {
@@ -71,7 +77,11 @@ in
       after = [ "network.target" ];
       wantedBy = [ "multi-user.target" ];
       serviceConfig = {
-        ExecStart = "${cfg.package}/bin/radicale -C ${confFile} -f";
+        ExecStart = concatStringsSep " " ([
+          "${cfg.package}/bin/radicale" "-C" confFile
+        ] ++ (
+          map escapeShellArg cfg.extraArgs
+        ));
         User = "radicale";
         Group = "radicale";
       };