Use Cobra Subcommands

[patrick-ogrady]

Is your feature request related to a problem? Please describe.
In the rosetta-cli, we use : to access subcommands instead of Cobra's native handling for this.

Describe the solution you'd like
Use subcommands properly (rosetta-cli view:block -> rosetta-cli view block). This will allow users to run rosetta-cli view -h to print all view child commands.

[godcloutier]

I think view:block command:subcommand pattern is better and avoids confusion personally but im used to that pattern so maybe other people will think differently