Convert link colors to rgb

Prerequisites

• I have searched for duplicate or closed feature requests
• I have read the contributing guidelines

Proposal

a {
  color: rgba(var(--bs-link-color), var(--bs-link-opacity));
}

a:hover {
  color: rgba(var(--bs-link-hover-color), var(--bs-link-hover-opacity));
}

Motivation and context

It will help with link styling. Also we will be able to do something like this:

a {
  text-decoration: var(--bs-link-line, underline) var(--bs-link-style, initial) rgba(var(--bs-link-color), var(--bs-link-line-opacity, 1));
  // and for the hover state
}

@each $style in (solid dashed dotted) {
  .link-#{$style},
  .link-#{$style}-hover:hover {
    --bs-link-style: #{$style};
  }
}