Update for release

Add SinglyLinkedList Data Structure Class (#1)

* Add SinglyLinkedList with push method

* Add Pop to SinglyLinkedList

* Add lessons learned to README

* Add todo methods and snub tests

* Add shift method to SinglyLinkedList

* Add unshift method to SinglyLinkedList class

* Add get method to SinglyLinkedList

* Add link to SinglyLinkedList README

* Add set method to SinglyLinkedList

* Add insert and remove methods to SinglyLinkedList

* Add reverse method to SLL

* Make methods private and remove optional chaining

* Update method names

* Update tests

* Add list v array to README

* Update class to use TS private modifier

* Update tests to utilize beforeEach

Add Github packages workflow