Support left-file coordinates in repo_create_pull_request_thread

[LycheeCattie]

Summary

Extend repo_create_pull_request_thread to support left-file coordinates so automated PR reviewers can create inline comment threads on deleted files. Deleted content only exists on the left (base) side of a diff, so right-file coordinates alone are insufficient for anchoring comments on removed lines.

Parameters

Add the following optional parameters to repo_create_pull_request_thread (create action), mirroring the existing right-file coordinate support:

• leftFileStartLine
• leftFileStartOffset
• leftFileEndLine
• leftFileEndOffset

These should map to the Azure DevOps CommentThreadContext fields leftFileStart and leftFileEnd, which are already supported by:

• The Azure DevOps Comment Threads API
• The official azure-devops-node-api (GitApi.createThread / CommentThreadContext)

Rules

1. Adhere strictly to existing project standards and coding conventions.
2. Ensure each tool/function exposes all API parameters (required and optional).
3. Use the official Azure DevOps Node API to interact with the APIs.

Special treat

[danhellem]

This is not something that has been requested by anyone else. I am going to add this to our backlog for future consideration if it gets more users asking for it.