78. convert HEX color to RGBA

Suppose you write some CSS code, you need to set colors. You can choose hexadecimal notation #fff or Functional notation rgba(255,255,255,1).

Can you write a function to convert hexadecimal notation to functional notation?

hexToRgb('#fff')
// 'rgba(255,255,255,1)'

1. Alpha channel should have maximum 2 digits after decimal point, round up if needed.
2. Don't forget to do input validation