Honor proxy configuration on remote end

[psy-q]

:RemoteStart fails with the following error:

curl: (28) Failed to connect to github.com port 443 after 136255 ms: Couldn't connect to server

curl itself works fine in an interactive shell session, it honors HTTPS_PROXY. Perhaps remote-nvim is not using a shell that processes ~/.profile, ~/.bash_profile or the like and so HTTPS_PROXY is unset in its environment.

Describe the solution you'd like
:RemoteStart should be able to install NeoVim on the remote by honoring the proxy settings.

Describe alternatives you've considered
Using offline mode. But this shouldn't be required in this case as the remote system can reach webservers (including GitHub) via HTTPS proxy.

Even when using offline mode, NeoVim will be unable to start properly if the configuration requires web access. For example, lazy.vim's cloning of plugins from GitHub via HTTPS will fail as it's missing the HTTPS_PROXY env var in its environment.