Define and optimize alias definition in OptimizedPhpArrayDumper

Problem/Motivation

OptimizedPhpArrayDumper doesn't define the alias property it uses for local storage and caching of container aliases.
Additionally, it builds the list of aliases twice instead of using that cache during array building.

Proposed resolution

Define the property and optimize the array build.

Remaining tasks

Review patch.

User interface changes

n/a

API changes

n/a

Data model changes

n/a

Release notes snippet

n/a