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>

String/AlternativeStringArrange.js

@@ -22,7 +22,10 @@ const AlternativeStringArrange = (str1, str2) => {
   // get second string length.
   const secondStringLength = str2.length
   // absolute length for operation.
-  const absLength = firstStringLength > secondStringLength ? firstStringLength : secondStringLength
+  const absLength =
+    firstStringLength > secondStringLength
+      ? firstStringLength
+      : secondStringLength
 
   // Iterate the character count until the absolute count is reached.
   for (let charCount = 0; charCount < absLength; charCount++) {