Implement correct entity resolving

[nielstron]

Is your feature request related to a problem? Please describe. If i.e. the unit "speed of light day" is entered, its entity is unknown even though it is actually known as it is "length". As quantulum3 does not expand all units to their very basic entities and shortens results (by resolving positive and negative powers), the result remains unknown.

Describe the solution you'd like In get_entity_from_dimensions the dimension information should be brought down to the very last basic entities, then unit shortening should happen (i.e. as above, time^-1 and time^1 should be removed)

Describe alternatives you've considered

Additional context