[#581] Determine unique alias automatically

Description

Problem: Oftentimes users don't care about specific alias for the newAddress or newAddressFresh. Such a requirement is sometimes inconvenient and reduces the chances that money will be reused.

Solution: Make it possible to determine unique alias automatically. In order to do that, a wrapper over AliasHint with the default constructor was added. Counter for such default aliases provides an ability to generate unique aliases per nettest scenario.

Related issue(s)

Resolves #581 (closed)

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