Fix order of deletion for files/dirs in ResolveMerger

Fix order of deletion for files/dirs in ResolveMerger

Before, the paths to delete were stored in a HashMap, which doesn't have
a particular order. So when e.g. both the file "a/b" and the directory
"a" were to be deleted, it would sometimes try to delete "a" first. This
resulted in a failed path because File#delete() fails when a directory
isn't empty.

With this change, an ArrayList is used for storing the paths to delete.
The list contains the paths in a top-down order, as defined by the order
of processEntry. When the files are deleted, the list is iterated in
reverse, ensuring that all files of a directory are deleted before the
directory itself.

Bug: 354099
Change-Id: I6b2ce96b3932ca84ecdfbeab457ce823c95433fb
Signed-off-by: Robin Stocker <robin@nibor.org>