Allow shell access to attestation properties

The properties for attestation are congifured in build.prop files and
used by frameworks Build.java.
Allow app to access them from 'adb shell am'

Bug: 296168846
Test: m selinux_policy
Change-Id: Ie749cf5d621c03c21aa538f96a06d21680a61569
diff --git a/private/shell.te b/private/shell.te
index 1b859d1..aa6bef8 100644
--- a/private/shell.te
+++ b/private/shell.te
@@ -250,3 +250,6 @@
 # Allow shell to set persist.sysui.notification.ranking_update_ashmem property
 userdebug_or_eng(`set_prop(shell, persist_sysui_ranking_update_prop)')
 
+# Allow shell to read the build properties for attestation feature
+get_prop(shell, build_attestation_prop)
+