New Family of Lanthanide-Based Inorganic–Organic Hybrid Frameworks: Ln2(OH)4[O3S(CH2)nSO3]·2H2O (Ln = La, Ce, Pr, Nd, Sm; n = 3, 4) and Their Derivatives (New Family of Lanthanide-Based Inorganic–Organic Hybrid Frameworks: Ln2(OH)4[O3S(CH2)nSO3]·2H2O (Ln = La, Ce, Pr, Nd, Sm; n = 3, 4) and Their Derivatives)