[Tokens] add design tokens to project

Add style-dictionary and design tokens to NDS. Design tokens provide a single point of truth for all property/value pairs in styling. These tokens will eventually be used for all NDS custom properties, utility classes, and theming.

Consuming design tokens internally is out of scope; this ticket should only add properties files and the necessary configuration to build token distributions.

Problems design tokens will solve

We can update semantic-ui themes with correct values for redesigns (until we can get rid of it completely):
- https://github.com/narmi/design_system/pull/283
We can eliminate duplicated defaults from indigo and make institution settings read directly from design tokens from NDS to populate defaults.
- https://github.com/narmi/banking/pull/12181
Every styling property/value will have the same reference name across all software.
NDS can internally use design tokens to ensure consistent colors, font size, and layout across all components.
Design tokens can be consumed in any format we need, including react native.

Requirements

Naming should be as close as possible to familiar CSS property names

--<cssProperty>-<valueStep>, e.g. --color-red or --fontSize-xl

Value steps should follow consistent sizing conventions (t-shirt sizes: xxs,xs,m,l,xl,2xl).

Wherever possible, a "default" value step should be provided, aliased to a t-shirt size.

--fontSize-default should alias to --fontSize-m (or wherever 16px falls on the scale)

CTI dictionary structure

<root>/tokens/src/
├── Color/
│   ├── theme.json      // themable colors (primary/accent)
│   ├── brand.json      // narmi brand colors
│   └── text.json       // standard and inverted context text colors
├── Border/
│   ├── radius.json     // border radii
│   ├── color.json      // border colors
│   └── size.json       // border sizes
├── Layout/
│   ├── media.json      // sizing icons and images
│   └── spacing.json    // gutter sizes
└── Font/
    ├── family.json     // all font family values
    ├── weight.json     // font weights
    ├── size.json       // font sizes
    └── lineHeight.json // standard _relative_ line heights organized by type size

narmi / design_system