Added MKS-CGS-FPS Calculator

[aditya962]

Issue Id you have worked upon -

MKS - CGS - FPS #353

Briefly explain your program logic -

This calculator takes input of MKS unit, CGS unit or FPS unit and converts them in the other two remaining units of the following quantities: length, mass, time, area, force, etc.

Screenshots(Attach 2 screenshots of your own input and output) -

By raising this PR I affirm that -

• [x] My code follows the guidelines of this project.
  

• [x] I have performed a self-review of my own code.
  

• [x] I have commented my code.
  

• [x] My code gives the correct output.
  

• [x] I affirm that I strictly follow contributing guidelines and code of conduct.

[SarthakKeshari]

Congratulations 🎉 @aditya962 on your contribution. Thanks for adding value to this repository. 😊

Let's celebrate this fest 😃 by providing more developers 👨‍💻👩‍💻 an opportunity to contribute. Help us make this repository reach far and more by sharing this to your friends and colleagues.

Your efforts can make difference.

[SarthakKeshari]

Hey 👋, may you also encourage us by clicking the star icon on the repository main page. ⭐

[SarthakKeshari]

@aditya962, Impressive UI. Adding admin-appreciation points for the efforts and dedication shown. 👏👏