refactor(circular-progress): Refactor spinner layer and color animation This change allows users who want to use only one color spinner to discard the extraneous DOM elements associated with the other 3 colors.
refactor(circular-progress): Refactor spinner layer and color animation
This change allows users who want to use only one color spinner to discard the extraneous DOM elements associated with the other 3 colors.

It extracts 2 key animations into variables such that:
- The spinning animation is applied to the mdc-circular-progress__spinner-layer class only
- Both spinning + color change animations are applied to the mdc-circular-progress__color-{1,2,3,4} classes.

So the spinning logic no longer relies on the presence of any color classes.

PiperOrigin-RevId: 300197675

material-components/material-components-web,material-components/material-components-web,material-components/material-components-web