Allow overrides of targeted build arg names in matrix versions

Currently, matrix dependency/value versions are passed into a singular matrix image definition as build args at build time for matrix builds. These are hardcoded for dependencies to use the name {DependencyVersion.dependency.upper()}_VERSION in all caps. This may prove inflexible long-term if we wish to allow multiple dependencies of the same type to be passed as build args or if the naming proves restrictive.

Start by tracing the matrix build logic that passes dependency and value versions into the singular matrix image definition as build arguments. Define how callers can override argument names, including support for multiple dependencies of the same type, and verify that matrix builds still receive the intended values.