Add the DefaultItemAnimator, without change animations

Change animations cause the addition of another view to be able to
crossfade/interpolate the two. Disabling change animations prevents us
losing the focus when a header row changes due to expanding or
collapsing.

Test: verified locally
Bug: 183378651
Change-Id: I07837b41748b5206936321c08d376069fa81b363
1 file changed