Make clickable Expandables have a minimum (interactive) size (1/2)

This CL improves Expandable by making sure that expandables that expand
when clicked directly have a minimum size of 40dp and minimum
interactive size (touchable area) of 48dp. This is consistent with the
M3 components like buttons.

Bug: 230830644
Test: Manual
Change-Id: Iada048498ff4655406968d7dac5d13c948efaea1