[Lib] Implement additional type mixins

[xak]

The design system has presets for various types of text so these should be easily available for authors to access.

Value

• Different text types can use different weights and styles and those can be preprogrammed.
• Developers can rely on more specific mixins for different text types instead of having to learn the base "-1" to "6" system.
• The base type scale can now be concerned only with font-size and line-height.

See https://zpl.io/2GOBx9m

Proposal

• [ ] Remove the type, weight and transform values from the $fd-type map.

"0": #{14/$fd-type--base}rem 20/14, //14/20

• [ ] Create a mixins/_type.scss file to hold the mixins below.

We want to move to small mixin files grouped by functionality.

• [ ] Remove transform param from fd-type() mixin

@mixin fd-type($size: "0", $weight: default) {
}

• [ ] Add text type mappings to settings to match the styles with the base type sizes

$fd-type-controls: () !default;
$fd-type-controls: map-merge((
  "1": 1 regular,
  "2": 0 regular
  "3": -1 regular
), $fd-type-controls);

$type	$size	scale size	weight
control	1	1	regular
control	2	0	regular
control	3	-1	regular
title	1	5	light
title	2	4	regular
title	3	3	regular
title	4	2	regular
title	5	1	regular
title	6	0	regular
display	1	6	light
display	2	5	light
display	3	2	light

• [ ] Create convenience mixins for each text type — fd-text-control($size), fd-text-title($size), fd-text-display($size).

These mixins can call the core fd-type() mixin after looking up the proper values in the appropriate map.

• [ ] Add helpers for each text type, e.g., fd-has-text-control-1, fd-has-text-title-6, fd-has-text-display-2.