Add sanitizer support

[naftaly]

Summary

Adds support for Thread Sanitizer (TSan) and Address Sanitizer (ASan) to help detect bugs during testing.

• Thread Sanitizer: Detects data races and other threading issues
• Address Sanitizer: Detects memory corruption issues like buffer overflows and use-after-free

Changes

• Added new sanitizer input parameter to action.yml (accepts thread or address)
• Updated index.ts to pass -enableThreadSanitizer or -enableAddressSanitizer flags to xcodebuild when sanitizers are enabled
• Sanitizers only apply to test and build-for-testing actions
• Added documentation to README with usage examples
• Added CI workflow job to verify both sanitizers work correctly on macOS

Usage

- uses: mxcl/xcodebuild@v3
    with:
      action: test
      sanitizer: thread  # or 'address'

Note: Only one sanitizer can be enabled at a time.

[Copilot]

Pull Request Overview

This PR adds sanitizer support to the xcodebuild action, enabling Thread Sanitizer (TSan) and Address Sanitizer (ASan) for detecting bugs during testing. The implementation allows users to specify either "thread" or "address" sanitizer through a new input parameter.

• Added sanitizer input parameter with support for thread and address sanitizers
• Updated xcodebuild command generation to include appropriate sanitizer flags
• Added comprehensive documentation and CI verification

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/index.ts	Added sanitizer input handling and xcodebuild flag generation for test/build-for-testing actions
action.yml	Added new sanitizer input parameter with detailed description of options
README.md	Added sanitizer documentation with usage examples for both TSan and ASan
.github/workflows/checks.yml	Added CI job to verify sanitizer functionality on macOS

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[naftaly]

@mxcl Added the dist that weren't there and caused the failures.

[naftaly]

Thank you @mxcl