Add empty watchman config

[skevy]

Description

Motivation and Context

How has this been tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[Copilot]

Pull Request Overview

This PR adds an empty Watchman configuration file to enable file system watching capabilities in the project. Watchman is a file watching service that can trigger actions when files change.

• Adds a minimal .watchmanconfig file with empty JSON object

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