big-input-action custom control color binding issue

[bdarge]

Minimal reproduction of the bug with instructions:

color selection is not honored by big-input-action element.

<button mat-raised-button color="color" [disabled]="disabled" (click)="onClick()">
  <mat-icon *ngIf="fontSet && fontIcon && !faIcon" [fontSet]="fontSet" [fontIcon]="fontIcon"></mat-icon>
  <fa-icon *ngIf="faIcon" [icon]="faIcon"></fa-icon>
  <span *ngIf="label">{{label}}</span>
</button>

Expected behavior:

I should be able to set different colors for different actions. I think it should be

<button mat-raised-button [color]="color" [disabled]="disabled" (click)="onClick()">
  <mat-icon *ngIf="fontSet && fontIcon && !faIcon" [fontSet]="fontSet" [fontIcon]="fontIcon"></mat-icon>
  <fa-icon *ngIf="faIcon" [icon]="faIcon"></fa-icon>
  <span *ngIf="label">{{label}}</span>
</button>

Other information:

I would be willing to submit a PR to fix this issue:

[x] Yes (Assistance is provided if you need help submitting a pull request)
[ ] No