Refactor code to have common modules across cli and SDK

[raamb]

Vitaly's comment

I agree with @vforvalerio87 point that package hierarchy:

  snet-client-common
  ^               ^
  |               |
snet-cli   snet-client-sdk 

or

snet-client-common
    ^
    |
snet-client-sdk
    ^
    |
snet-cli

is more reasonable than

snet-cli
    ^
    |
snet-client-sdk

And it doesn't necessary mean re-implementing all from the scratch, it means moving code into separate package/repo.

Originally posted by @vsbogd in https://github.com/singnet/snet-cli/pull/192#issuecomment-458861442