bumpfee: Allow original change position to be specified

If the user used a custom change address, it may not be detected as a
change output, resulting in an additional change output being added to
the bumped transaction. We can avoid this issue by allowing the user to
specify the position of the change output.

src/rpc/client.cpp

@@ -259,11 +259,13 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "bumpfee", 1, "fee_rate"},
     { "bumpfee", 1, "replaceable"},
     { "bumpfee", 1, "outputs"},
+    { "bumpfee", 1, "reduce_output"},
     { "psbtbumpfee", 1, "options" },
     { "psbtbumpfee", 1, "conf_target"},
     { "psbtbumpfee", 1, "fee_rate"},
     { "psbtbumpfee", 1, "replaceable"},
     { "psbtbumpfee", 1, "outputs"},
+    { "psbtbumpfee", 1, "reduce_output"},
     { "logging", 0, "include" },
     { "logging", 1, "exclude" },
     { "disconnectnode", 1, "nodeid" },