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>

Maths/ModularArithmetic.js

@@ -8,7 +8,7 @@ import { extendedEuclideanGCD } from './ExtendedEuclideanGCD'
  */
 
 export class ModRing {
-  constructor (MOD) {
+  constructor(MOD) {
     this.MOD = MOD
   }
 
@@ -23,7 +23,7 @@ export class ModRing {
   /**
    * Modulus is Distributive property,
    * As a result, we separate it into numbers in order to keep it within MOD's range
-  */
+   */
 
   add = (arg1, arg2) => {
     this.isInputValid(arg1, arg2)