Ledger support

[faboweb]

Support for ledger nano.

• Design user flow
• Implement account creation
• Implement signing

[faboweb]

Needs to be implemented in #1339

[NodeGuy]

How about we close this because it's far off in the future?

[jbibla]

makes sense to me

[faboweb]

deal

[fedekunze]

Reopening as per discussion with @faboweb and @jleni and labeling high priority:

• implementation
• unit test integration

To Do:

1. Copy the logic of unit test on voyager
2. Add 2 cmds more here

[faboweb]

Let's spike first if this works.

[jleni]

You can use the provided library (ledger-cosmos-js) as a reference. That has unit tests to show how to get app version, etc. It should work both on backend/frontend.