CLI: Init working-groups commands family

[Lezek123]

Implements #598

Core functionality implemented:

• ./cli/bin/run working-groups commands family
• ./cli/bin/run working-groups:overview --group=GROUP command that displays working group leader and members/workers information (similar to working group overview in Pioneer)
• added reusable getRequiredLead and getRequiredWorker methods inside WorkingGroupsCommandBase class, which serve as both a gate that will prevent users without access (worker/lead) from trying to execute a command that requires it AND a way of retrieving lead/worker entity and member profile information associated with the selected CLI account (since there could be more than 1 worker associated with a given key, there is also a support for choosing one of the available roles in that case)

I also introduced a few general improvements:

• Default currency symbol and decimals for formatBalance are now set based on the values provided by the runtime when initializing the api (same way it's done within Pioneer)
• Added dev Alice and Bob accounts as "special" hidden accounts that can be selected using ./cli/bin/run accounts:choose --showSpecial (for easier testing)
• Added build script for joystream-cli workspace and fixed the tsconfig issue (jest vs mocha types conflict)

[mnaamani]

Looks good, I tested on linux, still doesn't work on my mac. I only left a comment but it should be good to merge.