feat: add funding txid and amount to LDK channel closed event

[rolznz]

Fixes #1197 (LDK only)

Adds new properties to the nwc_channel_closed event for both LDK and LND:

counterparty_node_url

Adds new properties to the nwc_channel_closed event to LDK only:

pending_balance
funding_tx_id
funding_tx_vout
funding_tx_url

CC @MoritzKa (to review the new event properties which we could show in the email)

[im-adithya]

tACK

[MoritzKa]

I created this copy and added the pending_balance information. I think it is more useful than the opening transaction, isn't it?

[rolznz]

@MoritzKa I think the opening tx is still useful for reference. Could we include it underneath the pending balance? or do you see some downside? (I know it's not optimal, but it's what we have)