hsmtool.c - Added new method to enable creation of hsm_file from cmd-line args

[bstin]

Creating a hsm_file with hsmtool is currently an interactive process in terminal where user is expected to make choices for language, typing in seed phrase, etc. This works well, but is difficult to utilize for automated installs (ie. Docker, unattended-installs, etc).

This adds a new method: generatehsmbyargs that allows the user to input all required args on command-line and generate the hsm_file without terminal interaction.

Also the documentation was lightning-hsmtool.8.md updated to include new method.

All existing functionality was preserved, this only added a new method.

[rustyrussell]

Sorry about the delay reviewing!

I prefer to extend generatehsm to take the cmdline args if they are present? That ensures that the language list stays consistent, for example.

[niftynei]

@bstin any update on this?

[vincenzopalazzo]

I prefer to extend generatehsm to take the cmdline args if they are present? That ensures that the language list stays consistent, for example.

For compatibility with another mobile wallet where people can import this list of words, I would like to have just English as an option, using different languages can cause lack with other wallets

[rustyrussell]

I rewrote this to extend the generatehsm command line instead.

[rustyrussell]

Rebased...