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

---------

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

Data-Structures/Array/NumberOfLocalMaximumPoints.js

@@ -33,10 +33,13 @@ const CountLocalMaximumPoints = (array, startIndex, endIndex) => {
 
   // handle the two halves
   const middleIndex = parseInt((startIndex + endIndex) / 2)
-  return CountLocalMaximumPoints(array, startIndex, middleIndex) +
+  return (
+    CountLocalMaximumPoints(array, startIndex, middleIndex) +
     CountLocalMaximumPoints(array, middleIndex + 1, endIndex)
+  )
 }
 
-const NumberOfLocalMaximumPoints = (A) => CountLocalMaximumPoints(A, 0, A.length - 1)
+const NumberOfLocalMaximumPoints = (A) =>
+  CountLocalMaximumPoints(A, 0, A.length - 1)
 
 export { NumberOfLocalMaximumPoints }