feat(icons): remove base64 transformation

[mohamedMok]

I have read the contributing guidelines

• Yes
• No

Does this PR introduce a breaking change?

• Yes
• No

Describe the changes

This PR removes the postcss-base64 plugin from our packages, for the following reasons:

• We want to make the use of our cssdevtools package optional
• The postcss-base64 plugin has been out of date for several months causing security warnings
• The use of base64 is not necessarily appropriate for inserting SVGs into CSS

Other information

Helpful links:

• https://css-tricks.com/probably-dont-base64-svg/
• https://codepen.io/tigt/post/optimizing-svgs-in-data-uris

[mohamedMok]

https://css-tricks.com/probably-dont-base64-svg/

[tiloyi]

Great job @mohamedMok ! 🔥 🔥 🔥 🔥

Do you think we could make the code of this function a little less verbose, by making only one return at the end of the function?

Something like :

@function inline-icons($icon, $fill) {
  $svg: '';

  @if $icon == "cross-16" {
    $svg: '<svg xmlns="http://www.w3.org/2000/svg" height="1rem" width="1rem" fill="#{$fill}" viewBox="0 0 16 16"><path d="M9.41 8l3.3-3.29a1 1 0 10-1.42-1.42L8 6.59l-3.29-3.3a1 1 0 00-1.42 1.42L6.59 8l-3.3 3.29a1 1 0 000 1.42 1 1 0 001.42 0L8 9.41l3.29 3.3a1 1 0 001.42 0 1 1 0 000-1.42z"/></svg>';
  }
  
  // ... 
  
  @return svg-encode($svg);
}