* If a type 1 folder has an mail folder as a parent (at any level),
it is also a mail folder (and therefore, we should have it in our
folder list)
* Before rejecting type 1 folders, look for parents and accept those
that are mail folders
* Add unit test to verify logic
Bug: 2978410
Change-Id: I44cda1d1c1fd7f3976af53a1672736201cc995ff