Add script for generate a new available account

[tmm360]

With a view to simplifying life for those who intend to use bee-clef with multiple accounts, and meanwhile a more complex and complete solution will come, add a bash script for generate a new account.

There are different commands necessary to add and initialize a new account, and these are: newaccount, setpw and attest, and each with specific parameters. A script could be very useful. Current scripts only try to generate first account, if it doesn't exist.

[vandot]

@tmm360 in this PR we added support for multiple account but only during initial installation #51
You need only newaccount and setpw it can be added
./scriipt.sh addnew will generate random password, add newaccount, setpw for it and restart bee-clef so it picks new account (maybe reset is not needed, need to confirm it)?

[tmm360]

I've managed to create new accounts manually in the meantime. Good for the addition, anyway a simple script for add a new account at any time would be handy