feat: juice ignore comments

[cossssmin]

This PR adds support for using special CSS comments to skip inlining rules or declarations, and even entire files/style blocks.

Closes #387.

Ignore entire file

Add a /* juice ignore */ comment on the first line in your CSS to skip inlining the entire file or style block:

/* juice ignore */
body { color: red; }
.test { color: blue; }

Ignore next rule

Add /* juice ignore next */ before any CSS rule to skip inlining that rule:

body { color: black; }

/* juice ignore next */
h1 {
  color: blue;
}

p { color: green; }

The h1 rule will not be inlined, but will be preserved when removeStyleTags: true. The body and p rules will be inlined normally.

Ignore next declaration

Add /* juice ignore next */ inside a CSS rule to skip inlining the next declaration:

.test {
  color: red;
  /* juice ignore next */
  font-weight: bold;
  font-size: 14px;
}

The color and font-size will be inlined, but font-weight will not. The rule with the ignored declaration will be preserved in a <style> tag when removeStyleTags: true.

Ignore blocks of code

Use start/end comment pairs to ignore multiple rules:

h1 {
  color: black;
}

/* juice start ignore */
h2 {
  color: pink;
}

h3 {
  color: lightcoral;
}
/* juice end ignore */

h4 {
  color: green;
}

The h2 and h3 rules will not be inlined but will be preserved in a <style> tag when removeStyleTags: true. The h1 and h4 rules will be inlined normally.