feat: add MCP protocol types and rmcp adapters

[bolinfest]

Currently, types from our custom mcp-types crate are part of some of our APIs:

codex/codex-rs/app-server-protocol/src/protocol/v2.rs

Lines 43 to 46 in 03fcd12

	use mcp_types::ContentBlock as McpContentBlock;
	use mcp_types::Resource as McpResource;
	use mcp_types::ResourceTemplate as McpResourceTemplate;
	use mcp_types::Tool as McpTool;

To eliminate this crate in #10349 by switching to rmcp, we need our own wrappers for the rmcp types that we can use in our API, which is what this PR does.

Note this PR introduces the new API types, but we do not make use of them until #10349.

---

Stack created with Sapling. Best reviewed with ReviewStack.

• chore: remove deprecated mcp-types crate #10357
• feat: replace custom mcp-types crate with equivalents from rmcp #10349
• -> feat: add MCP protocol types and rmcp adapters #10356