Move file_contexts for APEXes to under /system/sepolicy

For centralized development of sepolices, file_contexts files for APEXes
are all moved to under /system/seplicy.

Bug: 119034475
Bug: 113373927
Test: m apex.test com.android.tzdata com.android.runtime com.android.media
Change-Id: I9bf4874793db4dbdb75cbd759ae95f72d7281007

apex/apex.test_file_contexts

+/manifest\.json   u:object_r:system_file:s0
+(/.*)?            u:object_r:system_file:s0

apex/com.android.media_file_contexts

+(/.*)?                u:object_r:system_file:s0
+/manifest\.json   u:object_r:system_file:s0
+/lib(64)?(/.*)  u:object_r:system_lib_file:s0

apex/com.android.runtime_file_contexts

+#############################
+# APEX module manifest.
+#
+/manifest\.json          u:object_r:system_file:s0
+
+#############################
+# System files
+#
+(/.*)?                   u:object_r:system_file:s0
+/bin/dex2oat(d)?         u:object_r:dex2oat_exec:s0
+/bin/dexoptanalyzer(d)?  u:object_r:dexoptanalyzer_exec:s0
+/bin/profman(d)?         u:object_r:profman_exec:s0
+/lib(64)?(/.*)?          u:object_r:system_lib_file:s0

apex/com.android.tzdata_file_contexts

+/manifest\.json          u:object_r:system_file:s0
+
+(/.*)?                   u:object_r:system_file:s0
+/etc(/.*)?               u:object_r:system_zoneinfo_file:s0
+