Use Cobra Subcommands

**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.