DO NOT MERGE: Allow sepolicies granting bootanim exec on /oem.

This is a backport of
https://android-review.googlesource.com/#/c/platform/system/sepolicy/+/458738/

since domain.te moved from ./domain.te to ./public/domain.te a straight
patch won't work.

(cherry picked from commit I6462bf510562eb3fb06304e50b68fba05d37b285)

Bug: 37992717
Test: Tested with Iot sepolicies in effect and bootanim can exec.
Change-Id: I387243d1d35a1240bbb64561e3a72f150c1f2a2c