Useful for asserting how many inputs we're contributing

if the utxo can't pay for its own fees, dont put it in the tx

Changelog-Changed: JSONRPC: fundpsbt will not include UTXOs that aren't economic (can't pay for their own fees), unless 'all'

Adjust our total available funds downward, to account for the fees we'll
be charged to spend them.

Make sure that 100% available actually puts in 100% of what we can add
(note that this isn't 'all' -- we don't include uneconomic utxos)

If we don't put funds into a channel, say why in the logs. Should make
it a bit easier to figure out what's going on.

If l2 didn't get FUNDING_LOCKED from l1 before it disconnected, it
won't be in state CHANNELD_NORMAL: it will be in DUALOPEND_AWAITING_LOCKIN.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>