Clean up use of AviaryValues in the middle-end of Aviary

[jkirk5]

Desired capability or behavior.

from @johnjasa: In some places within Aviary, especially where we go from user-facing phase_info to the inner guts of phase instantiation, we use AviaryValues object to simplify the units and data handling. We should standardize this usage throughout the middle-end of Aviary and ensure that we're taking advantage of the units conversion capability everywhere where it's possible.

Is your feature request related to a problem? Please describe.

No response

Associated Bug Report

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[jkirk5]

This should be investigated further - also need to consider if we want to use NamedValues instead of AviaryValues to ensure compatibility with variables not in the hierarchy (I believe many of the phase_info keys are not intended to be added to the hierarchy)