添加了自定义的ApplicationDbContext 和ApplicationUser ,并添加了Identity认证后，会出现
InvalidOperationException: Unable to resolve service for type 'Microsoft.AspNetCore.Identity.UserManager`1[Microsoft.AspNetCore.Identity.IdentityUser]' 错误
需要在解决方案中搜索IdentityUser，把相关网页上注入的IdentityUser改为ApplicationUser