Fix SS58 Warnings in Message Generator Scripts

[HCastano]

The message generator scripts got missed with some recent CLI updates. This updates them
to make sure they indicate a remark-payload when neccessary.

Tomek sniped these changes (and the fixes suggested by Slava) with #868.

Gonna salvage my green square by morphing this into just fixing some warnings related to wrong SS58 account encodings.

[svyatonik]

There are a few issues with this (which are mostly introduced in other PRs, but probably must be fixed here):

1. remark-payload is marked as conflicts_with("remark_size"), so you can't (actually can, but see (2)) use both here - in this case the --remark_size will be ignored;
2. conflicts_with("remark_size") and conflicts_with("remark_payload") should actually be conflicts_with("remark-size") and conflicts_with("remark-payload") (i.e. underscore -> hyphen). Right now this declaration doesn't work;
3. since remark_payload is now required, I don't see any point in keeping this payload generation. But actually I'd prefer to keep this and mark remark_payload as Optional<>.

[tomusdrw]

That's incorrect. remark-payload should not be required, it should be possible to do either:

$0 remark # default remark payload generated
$0 remark --remark-size <SIZE> # remark payload of given size is generated
$0 remark --remark-payload <BYTES> # explicit remark payload is being sent

I'm pretty sure I tested that, but will take a look again and add some test cases to make sure it works correctly, but the change was meant to be 100% backwards compatible.

EDIT: Indeed it does not work correctly, I don't know what the hell I was testing :D #868 to the rescue.