Fix bold text bug in NumberPicker

To draw its numbers, NumberPicker is using the original typeface of its
input TextView. This gets the wrong Typeface if bold text is enabled.

Fix this by using the TextView's TextPaint typeface. (This TextPaint is
never null).

See videos in bug for before and after comparisons.

Bug: 318304896
Test: manual
Flag: android.widget.flags.fix_unbolded_typeface_for_numberpicker
Change-Id: I9b45738291d6e8a12693dc02d2c3e32ac5952aec