Enable FastMCP to filter tools, prompts, resources using a fine grained policy

Description

The authorization protocol allows MCP to implement course grained authorization checks e.g. a principal can/cannot access the server.

For advanced use cases though it is useful to be able to limit access on a per tool/resource/prompt basis.

There are a range of authorization tools that can be used however rather than being specific I suggest it is better to provide a plugin API that allows providers to pick their underlying authorization approach.

I have a patch that shows this idea, I'll open a draft pull request to illustrate the idea and allow for further testing & refinement.

References

No response

首先审查细粒度授权提案以及 issue 中提到的补丁，然后将其与 MCP 授权协议进行比较。当 FastMCP 提供一个 provider plugin API，能够分别独立地允许或拒绝对工具、提示和资源的访问，并通过测试完善这一方案时，工作就完成了。