feat(openapi): implement rest api tool (part 3)

[AmaadMartin]

Link to Issue or Description of Change

Problem:
Developers lacked a dynamic BaseTool class capable of mapping LLM function call arguments to REST API paths, headers, query params, and payloads.

Solution:
Implemented RestApiTool (Part 3 of 4):

• rest_api_tool.ts: A robust tool implementation that leverages operation definitions to format HTTP requests, resolve credentials using ToolAuthHandler, execute API calls, and format responses.

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Summary of passed results:

• Unit tested argument formatting, query param mapping, auth handling, and dynamic tool schema generation.
• Actual Line Coverage by File:
  • rest_api_tool.ts: 95.78%

Checklist

• I have performed a self-review of my own code.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.