bug(material/chips): single-select chips visually communicate selected state with color alone (WCAG 1.4.1)

[zarend]

Description

single-select chips visually communicate selected state with color alone. It should be visually communicated with more than just color.

https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-without-color.html

Reproduction

Steps to reproduce:

1. open https://material2-dev.web.app/mdc-chips
2. Navigate to "Selectable Chips" demo
3. Under "Single selection", click "Medium"

Expected Behavior

selected state of "Medium" is visually communicated with more than color alone

Actual Behavior

color of "Medium" changes to indicate selected state

[zarend]

#25890 fixed this issue

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