feat: enhance address formatting in staking transactions

[uniyalabhishek]

From @matevz in Slack: there is one more transaction that needs love, e.g.

$ oasis acc allow paratime:sapphire 10 --account test:alice
You are about to sign the following transaction:
Method: staking.Allow
Body:
  Beneficiary:   oasis1qqczuf3x6glkgjuf0xgtcpjjw95r3crf7y2323xd
  Amount change: +10.0 TEST
Nonce:  54
Fee:
  Amount: 0.0 TEST
  Gas limit: 1286
  (gas price: 0.0 TEST per gas unit)

Network:  testnet
ParaTime: none (consensus layer)
Account:  test:alice

Beneficiary above should be paratime:sapphire (oasis1...)

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[matevz]

This seems very hacky. Account names should be added to the pretty printing code in oasis-core, for example
https://github.com/oasisprotocol/oasis-core/blob/master/go/oasis-node/cmd/stake/allowances.go#L90

Other consensus transactions like staking.Transfer for transferring ROSE should also use named accounts then. No need to support the newly added ethMap in ctx though, because those cannot sign consensus transactions.