Centralize logic related to units and conversion

[kennyweiss]

We have logic in Klee, in the Quest Open Cascade reader and in the shaping tutorial related to units and conversions between them.
We should centralize this logic in core and add some tests.

See:

• https://github.com/LLNL/axom/pull/1486/files#r1907564996
• https://github.com/LLNL/axom/blob/develop/src/axom/klee/Units.hpp
• Adds a tutorial on shaping and related capabilities #1656 (comment)