Add exFAT support; unify behind "sdcard_type".

We're adding support for OEMs to ship exFAT, which behaves identical
to vfat.  Some rules have been manually enumerating labels related
to these "public" volumes, so unify them all behind "sdcard_type".

Test: atest
Bug: 67822822
Change-Id: I09157fd1fc666ec5d98082c6e2cefce7c8d3ae56
diff --git a/private/app_neverallows.te b/private/app_neverallows.te
index 4b79060..3bdbfb1 100644
--- a/private/app_neverallows.te
+++ b/private/app_neverallows.te
@@ -93,9 +93,7 @@
 # application un-installation.
 neverallow { all_untrusted_apps -mediaprovider } {
   fs_type
-  -fuse                     # sdcard
-  -sdcardfs                 # sdcard
-  -vfat
+  -sdcard_type
   file_type
   -app_data_file            # The apps sandbox itself
   -media_rw_data_file       # Internal storage. Known that apps can