Remove PermissionStartOnly where possible and replace with bitcoinrpc

Remove PermissionsStartOnly for bitcoind and spark-wallet (it was never
needed there)

Give reason for PermissionsStartOnly in lightning-charge

Replace PermissionsStartOnly in clightning, electrs and liquid

modules/lnd.nix

@@ -163,6 +163,7 @@ in {
     users.users.lnd = {
       description = "LND User";
       group = "lnd";
+      extraGroups = [ "bitcoinrpc" ];
       home = cfg.dataDir; # lnd creates .lnd dir in HOME
     };
     users.groups.lnd = {};