Support solana addresses for owner and payer

[madninja]

For legacy usage support this supports both helium public keys as well
as solana addresses.

Fixes #460

[madninja]

@jthiller so the new output from the add cli here will now not display the fees since they're all determined by the network.. It'll also display owner and payer as Solana keys instead of the helium equivalent regardless of whether the user passed in legacy helium owner/payer or solana keys.

eg. output:

{
  "address": "helium_key",
  "mode": "dataonly",
  "owner": "solana_key",
  "payer": "solana_key",
  "txn": "xxx"
}

[jthiller]

Lovely! I'll update the docs

[jthiller]

Fixes #457

Edit: sad, I don't seem to be able to link the issue