[#936] Add an Ord instance for AddressWithAlias

Description

Problem: while there's no single well-defined ordering for AddressWithAlias, there is an ordering, and it's useful to have an Ord instance on it, so that it could be used e.g. as a Map key.

Solution: add the instance. Also explain the motivation for this type's existence and how its Ord instance is arbitrary.

Related issue(s)

Resolves #936 (closed)

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