Fix Y2038 issue in DateUtils.isToday()

Before this change isToday() would stop working in Y2038
because android.text.format.Time doesn't work after Y2038.

This commit fixes the code by using java.time classes that
are Y2038 safe.

Bug: 16550209
Test: atest android.text.format.cts.DateUtilsTest
Change-Id: Ied339a694819c308add8645c7434b645dc1ccdde
1 file changed