[MatStepper] Add support for custom animation duration timing

[ivandevp]

Feature Description

Currently, transition between steps are fixed in the stepper-animation.ts (225ms to Vertical Stepper and 500ms to Horizontal Stepper). It would be great to have an input for the animationDuration the same way the MatTab component works.

Use Case

When using an stepper it can look like this:

<mat-vertical-stepper #linearVerticalStepper="matVerticalStepper" [animationDuration]="500">
</mat-vertical-stepper>

<!-- or -->

<mat-horizontal-stepper #linearHorizontalStepper="matHorizontalStepper" 
                                       animationDuration="800ms">
</mat-horizontal-stepper>