Support 2025-03-26 MCP spec, and MCPs from URLs

[zachdaniel]

The latest version of the spec describes both stdio driven MCP Servers as well as servers that communicate over streaming HTTP, and support authentication. I'm working on an MCP server and naturally would rather not implement the outdated version of the spec just to test it with Zed 😆

Latest spec, for context: https://modelcontextprotocol.io/specification/2025-03-26

[imumesh18]

I guess it will be better for zed to move to https://github.com/modelcontextprotocol/rust-sdk instead of it's own implementation in long run to avoid these issues