Switches to using validateJSON

[Atomic-Germ]

Related issue

Closes #1052

Context / Background

We were using an RYO solution, and this moves us to validateJSON.

What change is being introduced by this PR?

• js/validate-json.js -> js/validate-json.mjs
• Adjusted js/import-export.mjs so that it uses validateJSON exported from js/validate-json.mjs
• Removed the old bits and associated tests.

How will this be tested?

All automated tests should still pass. The app should refuse to import a broken ttldb file.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
js/import-export.mjs	100.00% <100.00%> (ø)
js/validate-json.mjs	100.00% <ø> (ø)

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[araujoarthur0]

Please add a meaningful self-descriptive name to the PR.

[tupaschoal]

Could you redo the first commit to use git mv instead? Then it will be recorded as a file rename, instead of a file deletion + file addition.

Other than that seems fine, since validateJSON has pretty good test coverage on its own.

[tupaschoal]

Thank you!