label boot animations on oem with bootanim_oem_file

Bootanimation only access boot animation files on oem. Label
these files with bootanim_oem_file and remove oemfs file allow rule.

Also allow mediaserver and app to read this new label as they can access
/oem/media folder.

Bug: 324437684
Test: Confirm that boot animation on oem is shown without violations
Change-Id: I940ccde9391a5daa920f31926d32e68b1de5b7eb
diff --git a/private/file_contexts b/private/file_contexts
index 7d9660b..3a65d81 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -457,6 +457,9 @@
 
 /oem(/.*)?              u:object_r:oemfs:s0
 /oem/overlay(/.*)?      u:object_r:vendor_overlay_file:s0
+/oem/media/bootanimation.zip            u:object_r:bootanim_oem_file:s0
+/oem/media/shutdownanimation.zip        u:object_r:bootanim_oem_file:s0
+/oem/media/userspace-reboot.zip         u:object_r:bootanim_oem_file:s0
 
 # The precompiled monolithic sepolicy will be under /odm only when
 # BOARD_USES_ODMIMAGE is true: a separate odm.img is built.