Adjust Chip Mixin to use correct Accent Color

[emclaug2]

Describe the bug

Our mixin for the styling mat chips is using the incorrect palette color for accent chips.
In the image below, I've created a custom theme that uses green as primary, blue as accent, red as warn.

What is the expected behavior?

The accent chips should have no reference to the color green & should be blue in all variants.
Specifically see the stroked accent chips, the background is a shade of green.

What are the steps to reproduce?

Run the themes demo, but update the accent color palette to be a custom color (yellow, purple) and observe it not being used in the showcase chip example.

Screenshots or links to minimum reproduction example

Environment

Windows Chrome

Anything else to add?

No

[jeffvg]

we can update this later