Prettier, Husky, Fresh Contributing guide, rimraf for cross-platform

[asgvard]

This PR includes:

• Prettier is enforced via Husky pre-commit and CI step
• Prettier formatting fixes are also included in this PR (thus so many files changed)
• rimraf is used instead of rm -rf for cross-platform use
• Updates to CONTRIBUTE.md with more details about the repo structure, tools, codestyle requirements

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[changeset-bot]

⚠️ No Changeset found

Latest commit: bd67ca1

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[asgvard]

No changeset here, only internal scripts and formatting on demo app index.html

[predikament]

LGTM