fix(hnsstats): improve error handling and logging for VFP port counters

[ritwikranjan]

Description

This pull request includes several improvements and error handling enhancements in the hnsstats package for Windows. The changes focus on better error reporting and wrapping errors with more context.

Error Handling Improvements:

• pkg/plugin/windows/hnsstats/hnsstats_windows.go: Added a check to ensure portguid is not empty and logs an error if it is not found.
• pkg/plugin/windows/hnsstats/hnsstats_windows.go: Enhanced the error log message to include portguid when unable to find VFP port counters.

Dependency and Error Wrapping:

• pkg/plugin/windows/hnsstats/vfp_counters_windows.go: Imported the github.com/pkg/errors package for better error wrapping.
• pkg/plugin/windows/hnsstats/vfp_counters_windows.go: Wrapped errors with additional context when running vfpctrl commands.

Checklist

• I have read the contributing documentation.
• I signed and signed-off the commits (git commit -S -s ...). See this documentation on signing commits.
• I have correctly attributed the author(s) of the code.
• I have tested the changes locally.
• I have followed the project's style guidelines.
• I have updated the documentation, if necessary.
• I have added tests, if applicable.

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