Fix debounce function

[kylevv]

There is currently a method called debounce that lives in /lib/debounce.js. It is incomplete and needs to be fixed!

Debounce takes a callback function and wait time (ms) as arguments and returns a debounced version of the callback function. A debounced function will only invoke the original callback after the specified amount of time has elapsed without subsequent invocations of the debounced function. If a debounced function is called again before the first call has completed, the timer is reset.

Acceptance Criteria:

1. Running yarn test debounce results in tests passing.
2. You have written a skeleton method for someone else to work on.
3. You have written tests surrounding your skeleton method.
4. Running yarn lint does not print any errors to the console!
5. Optional: write one or two more tests surrounding the method you are solving to account for potential edge cases.

Please include the skeleton of a new method + an accompanying test for someone else to work on at the time of creating a pull request! A pull request will most likely be denied if it does not contain a skeleton method for someone else to work on! For more information, please read the Contributing Guide.

Thank you so much for your contribution!

[kylevv]

Requires #615 to be merged first.

[zenobht]

@BlakeGuilloud I want to work on this.

[BlakeGuilloud]

You got it @jbharat . thanks