Add --bitcoin-rpcclienttimeout CLI parameter

[s373nZ]

This is a first pass at #2817. It adds a --bitcoin-rpcclienttimeout parameter to bcli. It seems those parameters are automatically pulled in as lightningd parameters as well. Instead of setting the default value at 900 per the bitcoind, we set it to match the retry_timeout and then choose the maximum value from arguments gathered by the user.

Don't have much experience in C, but open to learn and contribute to this project where I can.

[cdecker]

Very nice change, thanks for contributing @s373nZ. It just missed the release window for v24.02, but I'll mark it for inclusion in v25.05 :+1:

[s373nZ]

@cdecker Gentle reminder -- is this still slated for inclusion in v25.05?

[cdecker]

@cdecker Gentle reminder -- is this still slated for inclusion in v25.05?

@endothermicdev is the release captain for this release so it'll be his decision, buy I'm happy to shepherd this one through if it qualifies (marked for inclusion and I'm volunteering to rebase and/or fix breakage if conflicts arise).

[endothermicdev]

Looks good. Nit: rather than passing through the bitcoind sematics, could the CLN option be named something similar to the existing bitcoin-retry-timeout? Maybe just bitcoin-rpc-timeout? Sorry to bikeshed.

[s373nZ]

@endothermicdev I noticed that the rpc* parameters to bitcoind seemed to follow a slightly different naming convention:

• bitcoin-rpcuser
• bitcoin-rpcpassword
• bitcoin-rpcport
• bitcoin-rpcconnect

and tried to follow in line with those, omitting the hyphenation -- a best guess. I'm happy to change the parameter name to bitcoin-rpc-timeout if you prefer, though.