feat(mat-progress-spinner): Allow Default Color settings

[wratho]

Feature Description

Mat Progress Bar already supports { provide: MAT_PROGRESS_BAR_DEFAULT_OPTIONS, useValue: { color: 'accent' } },
can we get the same for spinner? for example:
{ provide: MAT_PROGRESS_SPINNER_DEFAULT_OPTIONS, useValue: { color: 'accent' } },

Use Case

Our design wants all progress indicators to be Accent by default. At the moment we are able to default the bar, but we must manually set color="accent" on spinners.

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