Add selinux policy for new BinaryTransparencyService

Bug: 197684182

Test: Manually verified that BinaryTransparencyService is correctly
started and running.

Change-Id: I4eaf5698dd2edb428205afcd57c22502d56d2ec2
diff --git a/private/service_contexts b/private/service_contexts
index 2e79abb..f6316b0 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -328,6 +328,7 @@
 thermalservice                            u:object_r:thermal_service:s0
 tracing.proxy                             u:object_r:tracingproxy_service:s0
 translation                              u:object_r:translation_service:s0
+transparency                              u:object_r:transparency_service:s0
 trust                                     u:object_r:trust_service:s0
 tv_iapp                                   u:object_r:tv_iapp_service:s0
 tv_input                                  u:object_r:tv_input_service:s0