Backport: feat(mcp): export the json-rpc schema for requests and response

[github-actions]

This is an automated backport of #16553 to the release-v6.0 branch. FYI @aayush-kapoor
This backport has conflicts that need to be resolved manually.

git cherry-pick output

Auto-merging content/docs/07-reference/01-ai-sdk-core/index.mdx
CONFLICT (content): Merge conflict in content/docs/07-reference/01-ai-sdk-core/index.mdx
Auto-merging packages/mcp/src/index.ts
Auto-merging packages/mcp/src/tool/mcp-http-transport.ts
CONFLICT (content): Merge conflict in packages/mcp/src/tool/mcp-http-transport.ts
error: could not apply 3c30eb4c8e... feat(mcp): export the json-rpc schema for requests and response (#16553)
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
hint: Disable this message with "git config set advice.mergeConflict false"