HashLoader can accept rgb colors

[Roman178]

What changes are introduced?

HashLoader didn't accept rgb or rgba color (issue #582). I have added a new function that handles rgb color strings.

According to the docs in the mozilla (https://developer.mozilla.org/en-US/docs/Web/CSS/color_value/rgb), I tried to take into account all the cases, namely:
rgb(255 255 255 / 80%)
rgb(255 255 255)
rgb(255, 255, 255, 0.8)
rgb(255, 255, 255)

and their aliases rgba(...

I gave more priority to the opacity value contained in the rgb string. If the string does not contain this value, the opacity value is taken from the argument. I can change it if necessary.

Also I added new test cases for the function calculateRgba

I kindly ask you to review my PR. @davidhu2000

[davidhu2000]

@Roman178 thanks for this update, i'll take a look in the next week or two. Crazy busy these days. Appreciate the patience

[Roman178]

@davidhu2000 Thanks for the heads-up. No rush at all. I appreciate your time.