Add the category of countable-dimensional vector spaces

[ScriptRaccoon]

This PR adds the category of countable-dimensional vector spaces. It reduces the number of missing combinations from 631 to 625 (connected milestone).

Found 6 unique witnessed combinations by the supplied structures (Vect_c):

Directly witnessed:
- abelian ∧ ¬ℵ₁-accessible
- abelian ∧ ¬ℵ₁-cofiltered limits
- abelian ∧ ¬ℵ₁-filtered colimits
- split abelian ∧ ¬ℵ₁-accessible
- split abelian ∧ ¬ℵ₁-cofiltered limits
- split abelian ∧ ¬ℵ₁-filtered colimits

All properties have been decided.