[IBM Color Palette] Create palette V2 to satisfy AA & AAA accessibility requirements

[shixiedesign]

IBM Color Palette V1 has been in circulation and usage for a few months now and we have identified areas for improvement. This issue tracks the work done on IBM Color Palette V2.

Currently I've created a draft for Palette V2 that satisfies AA & AAA accessibility requirements at specific intervals:

Sketch file https://ibm.box.com/s/ehviuw5uumkk1i7tonymke3tuwd7x3y4 )

Palette is now with Sadek who is working on tweaking the hues to stay true across the spectrum of bright and dark.

[stale]

We've marked this issue as stale because there hasn't been any activity for a couple of weeks. If there's no further activity on this issue in the next three days then we'll close it. You can keep the conversation going with just a short comment. Thanks for your contributions.

[shixiedesign]

Not stale. Pending update from Sadek.

[shixiedesign]

Issue is finally complete! Final V2 color palette sketchfile: https://ibm.box.com/s/uuc0792cw6lg3ovkoeo8sec3nr6vfghh

Next steps:

• Decide best place to host the sketch & ai file for both Carbon and Language site, & update
• Update carbon-elements repo with new hex values [Colors] Update color palette values with Colors V2 #3737
• Update design kit (or export elements via @joshblack 's magic) [Colors] Update kit's color hexs to V2 carbon-design-kit#174
• Re-visit component enhancement issues: helper text [All fields and inputs] Helper text update #2329 , and buttons [Button] Support token & danger buttons fix #3736
• Look into the repercussions on Hover & Active colors. Do we still need tokens?
• Update Carbon site color page guidance
• Update Language site color page guidance