feat: Test running overhaul, switch to Prettier & reformat everything (#1407)

* chore: Switch to Node 20 + Vitest

* chore: migrate to vitest mock functions

* chore: code style (switch to prettier)

* test: re-enable long-running test

Seems the switch to Node 20 and Vitest has vastly improved the code's and / or the test's runtime!

see #1193

* chore: code style

* chore: fix failing tests

* Updated Documentation in README.md

* Update contribution guidelines to state usage of Prettier

* fix: set prettier printWidth back to 80

* chore: apply updated code style automatically

* fix: set prettier line endings to lf again

* chore: apply updated code style automatically

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Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Lars Müller <34514239+appgurueu@users.noreply.github.com>

Maths/NumberOfDigits.js

@@ -17,6 +17,7 @@ const numberOfDigit = (n) => Math.abs(n).toString().length
  * @see https://math.stackexchange.com/questions/2145480/how-does-the-logarithm-returns-the-number-of-digits-of-a-number
  * @author dev-madhurendra
  */
-const numberOfDigitsUsingLog = (n) => n === 0 ? 1 : Math.floor(Math.log10(Math.abs(n))) + 1
+const numberOfDigitsUsingLog = (n) =>
+  n === 0 ? 1 : Math.floor(Math.log10(Math.abs(n))) + 1
 
 export { numberOfDigit, numberOfDigitsUsingLog }