public async Task <User> Register(string username, string password)
{
AuthManager.CreatePasswordHashSalt(password, out var passwordHash, out var passwordSalt);
var user = new User()
{
Username = username,
PasswordHash = passwordHash,
PasswordSalt = passwordSalt
};
await _dbContext.Users.AddAsync(user);
await _dbContext.SaveChangesAsync();
return(user);
}