A Single-Center, 2-Part, Randomized, Double-Blind, Placebo-Controlled, Single-dose, Dose Escalation Study to Evaluate the Safety/Tolerability and Pharmacokinetics of a Single Dose of AD-6626 Administered Orally to Normal, Healthy Volunteers in Part A and the Safety/Tolerability, Pharmacokinetics, Pharmacodynamics and Preliminary Efficacy of a Single Oral Dose of AD-6626 Followed by Alcohol Administration in Normal, Healthy Volunteers With the Aldehyde Dehydrogenase 2 (ALDH2)*1/*1 (Wild Type) or ALDH2*1/*2 (Heterozygous) Genetic Variant in Part B