Statistics of 7‐Phenoxy-Substituted 3,4-Dihydro‐2H‐1,2,4-benzothiadiazine 1,1- Dioxides as Positive Allosteric Modulators of α‐Amino-3-hydroxy-5- methyl-4-isoxazolepropionic Acid (AMPA) Receptors with Nanomolar Potency