json_withdraw: fix change_outputs showing forever as unconfirmed in listfunds

[ghost]

Add the change output to owned_txfilter so its entry in db will
get a confirmation_height when detected in a block by filter_block_txs

before this commit, after a 'withdraw' command, 'listfunds' would
not show our change outputs as confirmed. This was mentioned in #2300

Modified the log message in wallet_extract_owned_outputs to
append 'CONFIRMED' when it is called with a blockheight arg.
To make distinction between (1st call) when adding owned output to the
db and (2th call) when confirmed in block.

[ghost]

To comment to myself: I am working/thinking about the semantics of commands like withdraw and fundchannel that try to broadcast and how to make it more user friendly in case of broadcast failure.

The withdraw command currently only adds/updates outputs in db when broadcast succeeds, but manual broadcasts are not detected.

My idea now is to handle withdraw and fundchannel in a similar way to take into account that users may manually rebroadcast failed tx and, in the meanwhile, prevent reusing outputs or perhaps even lock the wallet until bitcoin-cli problem is fixed. So we don't end up with stuck channels etc. that try to spend change outputs of failed broadcasts.

Will likely create separate (combined) PR for that and further discussion.

[cdecker]

ACK 0a445ed

[cdecker]

I'll add the space issue into a cleanup commit 😉