Added Shaker Sort Algorithm

[Pixelrick420]

This pull request adds the Shaker Sort (also known as Cocktail Shaker Sort or Bidirectional Bubble Sort) algorithm to the repository.

Implemented the Shaker Sort algorithm in javascript-algorithms/src/sorting/shakersort.js Included a brief description and time complexity analysis in the file’s docstring.

Shaker Sort is a variation of Bubble Sort that sorts bidirectionally : it passes through the list in both directions alternately.

Best Case: O(n) (already sorted) Average Case: O(n²) Worst Case: O(n²)

Space Complexity: O(1) (in-place)