Add spendable/receivable and is_local fields to the callback function
used in gossmods_from_listpeerchannels. This allows to do more fine
grained use of the listpeerchannels call.
The first use case is renepay, for which we need to ignore the htlc_max
of the local channels only.
Any file in this directory which is executable and whose name only
consists of alphanumeric characters, space, '.', '-' or '_' will be
automatically loaded when lightningd starts (unless suppressed with
commandline options).
56ac5eebef