Get rid of drawing hacks for search dialog suggestions

Before, SuggestionsAdapter parsed every HTML formatted
string three times, to support state-dependent colors
in <font> tags. Now that there is support in Html
for color resources (added in
https://android-git.corp.google.com/g/7441),
we can get rid of this code.

Also, SuggestionsAdapter had a special purpose view
for drawing background colors when suggestion items
were not selected or pressed. This change replaces that
code with a StateListDrawable of ColorDrawables.

Before this change, HTML parsing used ~17% (uncontrolled benchmark,
just did some random searching) of the system_process CPU.
This change should reduce that by 2/3, i.e. about ~11% total
system_process reduction.