[Tab] Skip calling ViewPager2#setCurrentItem() when the active page i…

[archer-n]

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Closes https://github.com/material-components/material-components-android/issues/1865.

The current TabLayoutMediator implementation has an issue that it invokes ViewPager2#setCurrentItem() when a user navigates between pages by a swipe operation. The method call aborts the scrolling animation that the user made and starts a new scroll animation when smoothScroll = true, or stops scrolling immediately when smoothScroll = false. Don't forget:

• [x] dentify the component the PR relates to in brackets in the title. Link to GitHub issues it solves. (closes
• [x] https://github.com/material-components/material-components-android/issues/1865)
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[drchen]

Hi Dan the change itself looks good to me. Can you help bring it through our internal code review?