Added an example 'wiper'

[Inv3nt0r1]

Hello all,
Myself Durgesh Pachghare, want to contribute to Arduino in the GSOC 2020. This is my sample PR which adds a simple example wiper.

Wiper example is similar to a car's wiper, where the wiper is activated on the application of a digital button.

[per1234]

Please do a Tools > Auto Format if using the Arduino IDE or Ctrl + B if using Arduino Web Editor to make the formatting of your code consistent with the style used in Arduino's official examples.

[Inv3nt0r1]

Thank you so much for your review.
I have added necessary changes and did the Auto-Format.

Requested changes have been made. Thanks!

[Inv3nt0r1]

Unnecessary commits are squashed into one.
Thank you

[CLAassistant]

All committers have signed the CLA.