Update on module code: generic and over quotient rings

[HechtiDerLachs]

An update on #1806 in March 2025. What still needs to be done:

• coordinates(v::FreeModElem{T}, M::SubModuleOfFreeModule{T}, task::Symbol='something') where {T<:MyRingElemType}: It has to be decided whether or not it is part of the requirements for the SubModuleOfFreeModule-layer to implement the methods with this particular signature.
• We have to clarify whether coordinates should return an SRow (or a Vector, or even a 1xn-matrix).
• cokernel does not return the projection map for morphisms of modules.
• Fix up comparison of morphism of modules with ring maps (See WIP in Some improvements on morphisms of modules #4706).