Add two utility function dfu-all and dfu-ls

[cuongnv]

• dfu-ls: list all dfu devices with serial number
• dfu-all: flash all dfu devices ( use in mass production flashing)

[nickray]

Hi @cuongnv, thanks for contributing to solo-python!

I think dfu-ls is already implemented in solo ls --all (or -a), can you confirm?

Generally, the solo command uses subcommands to implement functionality, not kebab-case commands as in your pull request. I would like to keep it that way, so the CLI API is consistent and discoverable.

Moreover, all commands that involve a key either

• check if there's exactly one key, in which case that one is operated on
• if there are multiple, error except if -s <serial number> (or --serial <serial number>) is passed

I agree it would be good to be able to operate on all keys (although error handling is a bit tricky). The logical choice to me would be -a/--all. An alternative would be -e/--every, what do you think?

For your dfu-all, I would suggest you implement such an --all flag (with synonym -a) for the existing solo program dfu command. Would that work for your use case?

For that, would additionally replace the -a synonym of --connect-attempts everywhere, e.g. with -c.

[cuongnv]

You are right, should do as you recommend to make more consistent and discoverable. :)