[Tabs] Make header pagination scroll faster

#### Feature Description

Consider the following example:
Browsing a page with 6 tabs on mobile (only 3 fit at a time).
To get to tab 6, you have to click the pagination arrow 3 times.
That's pretty slow. I would expect one click to show tabs 4, 5, 6.
You can try this on the first official [example](https://material.angular.io/components/tabs/examples) (add some tabs in StackBlitz).


#### Use Case

Making the app more convenient on mobile.

#### More info

The scrolling is handled in `_scrollHeader()` method in [paginated-tab-header.ts](https://github.com/angular/components/blob/master/src/material/tabs/paginated-tab-header.ts#L395):
_"Move the scroll distance one-third the length of the tab list's viewport."_
The simplest solution would be replacing `viewLength / 3` with `viewLength` or `viewLength * 3 / 4`.
Another option is to make this fraction configurable through an `@Input` similarly to [animationDuration](https://material.angular.io/components/tabs/api).

Start in src/material/tabs/paginated-tab-header.ts at the _scrollHeader() method, which currently moves the tab-list viewport by one-third of its length. Evaluate the proposed scroll distance or configurability, then verify that one pagination click can reveal the next group of tabs on the official tabs example, including the six-tab mobile case.

Written by the indexing model from the issue text.