lightningdevkit
Implement `invalid-parameters-error` in LSPS1 / LSPS2
When we dropped versioning support a new error type was introduced: invalid-parameters-error (see https://github.com/BitcoinAndLightningLayerSpecs/lsp/tree/main/LSPS0#-32602-invalid-parameters-error).
We currently don't return it, but should, at least if it's not too cumbersome.
Other implementors before mentioned that it's not trivial to do with serde, if it's too cumbersome we might want to bring it back to the spec group.
as discussed in PR https://github.com/lightningdevkit/rust-lightning/pull/4039, a change to BLIP-50 will be proposed to simplify the invalid-parameters error. the request will still fail if unknown params are found, but the error will no longer report which fields were unknown.
