feat: update docstrings with warnings, allow None for hash bytes, use…

[JPHutchins]

… --confirm flag

Have a better idea of this now, so I'm updating the language and how the command could be used. It can mostly be ignored by users since they'll just use smpgmr upgrade (which has its own problems).

smpmgr image state-write --help

 Usage: smpmgr image state-write [OPTIONS] [HASH]

 Request to write the state of FW images on the SMP Server.


╭─ Arguments ──────────────────────────────────────────────────────────────────────────────────╮
│   hash      [HASH]  SHA256 hash of the image header and body to mark for test swap and/or    │
│                     confirm (caution).                                                       │
│                     [default: None]                                                          │
╰──────────────────────────────────────────────────────────────────────────────────────────────╯
╭─ Options ────────────────────────────────────────────────────────────────────────────────────╮
│ --confirm          Confirm the image given by hash (caution) if it was provided, else the    │
│                    first image (the running image). CAUTION: It is recommended to only       │
│                    confirm an image that has already booted, which can be guaranteed by      │
│                    sending this command to an SMP server running in that application image   │
│                    (NOT the bootloader), and NOT providing the hash argument.                │
│ --help             Show this message and exit.                                               │
╰──────────────────────────────────────────────────────────────────────────────────────────────╯

FYI @tormodvolden Take a look if you have a chance and LMK if you agree.

Closes #78