Encode the full opening fee params object in the promise itself

[JssDWt]

All values in the opening fee params object are encoded (encrypted) into the promise itself. Sometimes new fields are added, and they are not returned by the client, because the client doesn't know about these fields yet. If the values are encoded inside the promise itself, the LSP only has to look at this field in order to extract the proper values. Even the ones that were not included by the client itself.

[JssDWt]

Related: BitcoinAndLightningLayerSpecs/lsp#94