v0.9.0: Add `utils` export; adjust lint rules; upgrade dependencies

🌎 External changes

• Publish new export utils and utility function ifEmpty().
• Adjust lint rules:
  • Turn off rule import/no-cycle due to cost and false positives.
  • Adjust rule import/no-unused-modules for Jest mocks to (a) no longer report unreferenced exports and (b) report missing exports.
  • Relax rule max-statements-per-line with an increased maximum of two across the board. Previously, the maximum was two for Jest mocks and tests, and one for everything else.
  • Exempt JSX files from rule multiline-ternary as it clashes with react/jsx-indent, which in turn clashes with indent.
  • Turn off rule react/jsx-props-no-spreading for TypeScript files, where prop spreading is safe.
• Implement new lint rules:
  • @typescript-eslint/consistent-type-exports
  • @typescript-eslint/consistent-type-imports
  • @typescript-eslint/no-duplicate-type-constituents
  • @typescript-eslint/no-import-type-side-effects
  • @typescript-eslint/promise-function-async

🧹 Chores

• Enable strict null checks for JavaScript.
• Upgrade dependencies.