Phytochemical Profiling of Ephedra alata subsp. alenda Seeds by High-Performance Liquid Chromatography—Electrospray Ionization—Quadrupole-Time-of-Flight-Mass Spectrometry (HPLC-ESI-QTOF-MS), Molecular Docking, and Antioxidant, Anti-diabetic, and Acetylcholinesterase Inhibition