fix(vhd-lib/VhdDirectory#writeChunkFilters): correctly overwrite chunk-filter.json

[fbeauchamp]

• writeChunkFilters would have crashed if filter file does not exists and we set a empty compression
• it would not have updated the filter file if used with a fs implementation respecting fs permissions flags

Check list

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• PR reference the relevant issue (e.g. Fixes #007 or See xoa-support#42)
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• CHANGELOG.unreleased.md:
  • enhancement/bug fix entry added
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