About a Mechanism for Name and Alias Deprecation

@doug-walker and I quickly discussed about the idea of a mechanism to deprecated colorspace names and aliases.

As part of the OpenColorIO Config for ACES, we have included the aliases many of the previous config for compatibility reason.

This is an approach that only leads to ever-growing aliases if there is no deprecation mechanism. It would thus be useful to flag as deprecated names and aliases.

The issue does not name any files, tests, or entry points. First clarify the intended deprecation behavior for colorspace names and aliases, including compatibility expectations, then identify the relevant configuration and lookup code and define tests for deprecated-name handling.

Written by the indexing model from the issue text.