Add flag for tokens not to be echoed in prepare.sh for Version Control module

[cpswan]

Is your feature request related to a problem? Please describe.
I'd like to be able to do demos without revealing my token to the audience

Describe the solution you'd like
prepare.sh should take a -s flag to be silent and not echo tokens to the terminal

Describe alternatives you've considered
Delete the token really quickly, but the length of the demo is already sufficient time for an attacker

Additional context
We already have this for the Shift Left module (as that was being used more for public demos)