Allowing search_code tool's project parameter to accept single string as input (#1126)

The change makes the project parameter accept either a single string or
an array of strings. When a single string is provided, it's
automatically transformed into a one-element array.

## GitHub issue number

1038

## **Associated Risks**

None

## ✅ **PR Checklist**

- [X] **I have read the [contribution
guidelines](https://github.com/microsoft/azure-devops-mcp/blob/main/CONTRIBUTING.md)**
- [X] **I have read the [code of conduct
guidelines](https://github.com/microsoft/azure-devops-mcp/blob/main/CODE_OF_CONDUCT.md)**
- [X] Title of the pull request is clear and informative.
- [X] 👌 Code hygiene
- [N/A] 🔭 Telemetry added, updated, or N/A
- [N/A] 📄 Documentation added, updated, or N/A
- [X] 🛡️ Automated tests added, or N/A

## 🧪 **How did you test it?**

Added unit tests for testing
Performed Manual Testing on the modified tools: 
Ex: 
<img width="1757" height="1198" alt="image"
src="https://github.com/user-attachments/assets/665ed735-b3dc-4864-a05c-ade214ad6df9"
/>

---------

Co-authored-by: Krishna Prasath D <krid@microsoft.com>
Co-authored-by: Dan Hellem <dahellem@microsoft.com>

Author: 3 people

src/tools/search.ts

@@ -22,7 +22,10 @@ function configureSearchTools(server: McpServer, tokenProvider: () => Promise<st
     "Search Azure DevOps Repositories for a given search text",
     {
       searchText: z.string().describe("Keywords to search for in code repositories"),
-      project: z.array(z.string()).optional().describe("Filter by projects"),
+      project: z
+        .union([z.string().transform((value) => [value]), z.array(z.string())])
+        .optional()
+        .describe("Filter by projects"),
       repository: z.array(z.string()).optional().describe("Filter by repositories"),
       path: z.array(z.string()).optional().describe("Filter by paths"),
       branch: z.array(z.string()).optional().describe("Filter by branches"),