基于策略的授权（简单版）：已注释

// 1【授权】、这个和上边的异曲同工，好处就是不用在controller中，写多个 roles 。
// 然后这么写 [Authorize(Policy = "Admin")]
/*
services.AddAuthorization(options =>
{
    options.AddPolicy("Client", policy => policy.RequireRole("Client").Build());
    options.AddPolicy("Admin", policy => policy.RequireRole("Admin").Build());
    options.AddPolicy("SystemOrAdmin", policy => policy.RequireRole("Admin", "System"));
    options.AddPolicy("A_S_O", policy => policy.RequireRole("Admin", "System", "Others"));
});
*/