invoices: return payment address and add index from addholdinvoice

[ErikEk]

Fixes: #4820. This pr extends the response from addholdinvoice to mimic that of the addinvoice response. It adds AddIndex and PaymentAddr to AddHoldInvoiceResp.

Fixes: #4820

[guggero]

Thanks for the PR. I think the r_hash doesn't make any sense here. See my comments below.

// EDIT: Maybe I should read the issue this is trying to fix first :/

[carlaKC]

Just some fixups needed in the rpc changes!

Thanks for the PR! Going to be very useful to have this surfaced.

[ErikEk]

Btw, this update changes one of the json response items from "pay_req" to "payment_request", as defined in the proto file. I thought it was worth it, to mimic the response from addinvoice, as closely as possible.

[guggero]

I think that's okay. Hopefully scripts use the gRPC interface directly and don't parse the output of lncli.

[ErikEk]

Code has now been updated.

[guggero]

LGTM, thanks 🎉

[guggero]

I think that's okay. Hopefully scripts use the gRPC interface directly and don't parse the output of lncli.

[carlaKC]

tACK

$ lncli addholdinvoice 74e03041f676fc0fe3d19980c6b7a06d947fbd91879b02c410fb8bf86cb79025                                                                                                                                                                          
{
    "payment_request": "lnbcrt1ps0d0empp5wnsrqs0kwm7qlc73nxqvddaqdk28l0v3s7ds93qslw9lsm9hjqjsdqqcqzpgxqyz5vqsp5se4cpj3qu29gnwr4xuyntc95q6w4kfk7j7zzx5vhy46pgqyzzx8s9qyyssq9ycn8ul5eugrftulj6wtgmhnge40epetcl5828kxvmsu2yz33huz0eeea28kwn0uhn4cu0pe97y0l45gwnaa0aagvwd8dtt7yx4wpmgpfm7ggk",
    "add_index": "11",
    "payment_addr": "866b80ca20e28a89b875370935e0b4069d5b26de97842351972574140082118f"
}