Add Ledger wallet support

[KingGorrin]

This PR adds support for the following:

• Added support for Ledger wallets
• Added Zenon Ledger Wallet v0.1.1
• Updated Zenon SDK v0.6.9 with wallet abstraction support

Limitations

• The following commands are not supported on Ledger wallets: wallet.createNew, wallet.createFromMnemonic, wallet.dumpMnemonic, wallet.export.

Tests

• Added manual test runs

Known issues

• A Ledger connection becomes invalid when another process opens a new connection to the Ledger. The invalid connection still responds to Ledger commands. The LedgerTransport throws a ResponseError when it detects invalid responses, but sometimes the response is valid but contains old data from memory. This can cause a Ledger command to return but with old data. The Ledger device is never actually called and in case of a signTx command no confirmation is asked. This issue will eventually cause an exception (for example when signing a transaction) and can only happen when creating multiple connections to the ledger.