proposal: make file api Portable

[wenxuwan]

What would you like to be added:

背景

当前的File接口很难做到可移植性，对于OSS来说，本身就有S3协议这种标准协议，因此本ISSUE提出通过Layotto的拓展API的能力，直接支持S3协议。

官方的阿里云OSS给出了接口的兼容列表，详情见AWS S3兼容性，因此S3协议的设计可以先根据这个兼容列表来做，一些不兼容的接口能力也允许用户调用，但会根据具体的服务提供商来实现。官方列出的接口经测试下来，也并不完整，有接口支持并未列出。本人已对增删改查Object接口做过测试。

设计

在进行接口设计前要理清楚一个问题，S3既然天然支持了可移植性，那么用户如果用S3的SDK编程，就天然具有了可移植性。Layotto要想抽象该套接口，最多也就是将S3接口给抄录下来，请求结构体中的数据基本都是动态参数，每次请求都可能不同，也没法将参数存放到配置文件中去。Layotto唯一能带来的优势能想到的就以下两点：
● AK，SK、EndPoint等信息的托管。
● 用户无需面向SDK开发，client初始化的逻辑可以封装到Layotto中。

基于上述的两个条件，我们需要做的事情就是将S3的结构体搬到pb里面去：

以GetObject为例，此处只是抽出来了部分参数，具体的参数可以全部拷贝过来，也可以看哪些常用的拷贝过来：

对于该接口因为已经测试过兼容性，因此直接使用aws的能力进行请求（此处先直接桥接到了现有的aws实现上）：

然后通过下面的方式将该S3Server注册到Layotto上。

[seeflood]

I propose we call it "AWS S3 API" instead of "File API" :)

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity in the last 30 days. It will be closed in the next 7 days unless it is tagged (pinned, good first issue or help wanted) or other activity occurs. Thank you for your contributions.

[github-actions]

This issue has been automatically closed because it has not had activity in the last 37 days. If this issue is still valid, please ping a maintainer and ask them to label it as pinned, good first issue or help wanted. Thank you for your contributions.

[github-actions]

This issue has been automatically closed because it has not had activity in the last 37 days. If this issue is still valid, please ping a maintainer and ask them to label it as pinned, good first issue or help wanted. Thank you for your contributions.

[seeflood]

进展:

• 接口适配了AWS跟阿里云
• UT覆盖率差0.7%，正在补充
• 社区代码review
• 跟生产用户沟通，把OSS底层实现迁移到新版接口上，达到真正的跨平台部署
• api-spec 代码review