fix(amazonq): add boundary check to UserModificationTracker to prevent IndexOutOfBoundsException

[evanliu048]

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Description

This PR improves the emitTelemetryOnSuggestion method in the CodeWhispererUserModificationTracker class. Specifically:

• Added validation for RangeMarker to ensure it is valid before processing offsets.
• Included checks for invalid offset ranges (e.g., startOffset or endOffset exceeding the document's length or being inconsistent).
• Added logging for invalid scenarios to aid debugging.
• Ensured graceful fallback by reporting telemetry with null modification percentage when encountering invalid ranges or documents.

Checklist

• My code follows the code style of this project
• I have added tests to cover my changes
• A short description of the change has been added to the CHANGELOG if the change is customer-facing in the IDE.
• I have added metrics for my changes (if required)

License

I confirm that my contribution is made under the terms of the Apache 2.0 license.

[rli]

#5187