feat(tokens): added ai tokens

[agliga]

Fixes #2122

• This PR contains CSS changes
• This PR does not contain CSS changes (It contains token changes only, css changes are on demo page only)

Description

• Added AI tokens, with gradients

Notes

• Had to use background instead of background-color for tokens demo part because gradients dont work with background-color
• Dark mode colors are the same as light mode.

Screenshots

Checklist

• I verify the build is in a non-broken state
• I verify all changes are within scope of the linked issue
• I regenerated all CSS files under dist folder
• I tested the UI in all supported browsers
• I did a visual regression check of the components impacted by doing a Percy build and approved the build
• I tested the UI in dark mode and RTL mode
• I added/updated/removed Storybook coverage as appropriate

[ArtBlue]

The changes look fine. I do have some questions though. In the design docs, I'm only seeing these used in icons, but the icons are going to be -colored and not dynamic and would not need these. Where else will they be used?

[agliga]

The changes look fine. I do have some questions though. In the design docs, I'm only seeing these used in icons, but the icons are going to be -colored and not dynamic and would not need these. Where else will they be used?

These can be used by teams. We're simply providing those variables for them to be able to use them in their app. Like we do for the scrim tokens.

[ArtBlue]

LGTM