[ENHANCEMENT] Rename `Box` and `Real` configuration types

[oerc0122]

Is your feature request related to a problem? Please describe. There is a standard name in crystallography for Box (fractional) and Real (absolute/cartesian) coordinates. Having these MDANSE-only names is confusing. (c.f https://en.wikipedia.org/wiki/Fractional_coordinates)

Describe the solution you'd like Standardise all names to Frac/Abs when referring to those properties.

In the first instance to maintain backwards compatibility leave aliases to old names.

Describe alternatives you've considered N/A

Additional context N/A