【特性】公共函数不应在swagger文档里面显示锁的图标

修复方式：ConfigureServices函数里添加`c.OperationFilter ();`
我个人实现方式：
```csharp
using Microsoft.AspNetCore.Authorization;
using Microsoft.OpenApi.Models;
using QingjiuServer3.Auth;
using Swashbuckle.AspNetCore.SwaggerGen;
using System.Collections.Generic;
using System.Linq;

namespace QingjiuServer3 {
public class SecurityRequirementsOperationFilter: IOperationFilter {
public void Apply (OpenApiOperation operation, OperationFilterContext context) {
if (operation == null || context == null)
return;
var requiredScopes = context.MethodInfo.GetCustomAttributes (true).OfType ().Select (attr => attr.Policy).Distinct ();

if (requiredScopes.Any ()) {
operation.Responses.Add ("401", new OpenApiResponse { Description = "Unauthorized" });
operation.Responses.Add ("403", new OpenApiResponse { Description = "Forbidden" });
operation.Description = $"{requiredScopes.First ()}
{operation.Description}";
operation.Security = new List {
new OpenApiSecurityRequirement {
[new OpenApiSecurityScheme {
Reference = new OpenApiReference { Type = ReferenceType.SecurityScheme, Id = "Bearer" }
}] = requiredScopes.ToList ()
}
};
}
}
}
}
```
然后如果没有标记MyAuth就不会显示锁的图标；标记后就会显示锁的图标。
我的MyAuthAttribute的Policy是为了给函数加上说明，比如【此函数只有管理员可访问】等，这个字符串将拼接在所有用户自定义的函数说明之前。这样做的好处是，用户不需要对所有函数的可访问性专门做一个描述。示例：用户描述是：`此函数用于登录`，Policy自动生成的字符串是`【此函数无需验证，任何人均可调用】`，那么最终文档效果是：
```
【此函数无需验证，任何人均可调用】
此函数用于登录
```