Add basic support for proxy

[seberm]

Get the proxy configuration from clightning configuration file and use it for all http/https connections.

We need to proxy all http/https trustedcoin connections via Tor in a nix-bitcoin project, see the PR here:

• https://github.com/fort-nix/nix-bitcoin/pull/597#issuecomment-1503099388

We currently set the Environment="HTTPS_PROXY=socks5://127.0.0.1:9050" and Environment="HTTP_PROXY=socks5://127.0.0.1:9050" env variables in a clightning systemd service configuration as a workaround:

• https://github.com/fort-nix/nix-bitcoin/pull/597/files#diff-05a8747f05b6c0eea6aa51bb5622bd456447d0b7d2c1b7c7ceaef43e7d3d9aebR22

[fiatjaf]

Looks good. Should I merge?

[seberm]

Hello @fiatjaf, we need to get the proxy value from the configuration provided by init method.

I think that this is not supported in current lightningd-gjson-rpc version. That's why I created this PR:

• https://github.com/fiatjaf/lightningd-gjson-rpc/pull/10

Please, let me know, what you think, feel free to make any changes. The golang is not my strong suit.

[fiatjaf]

Merged that one and published as v1.6.2.