Description: Define the set of topological magma morphisms (continuous magma
morphisms) between two topological magmas. If domain and codomain are
topological semigroups, monoids, or groups, then one obtains the set of
morphisms of these structures. This definition is currently stated with
topological monoid domain and codomain, since topological magmas are
currently not defined in set.mm. (Contributed by BJ, 10-Feb-2022)