Allow system server to set dynamic ART properties.

This change gives a new type (dalvik_dynamic_config_prop) to some ART
properties such as dalvik.vm.dex2oat-cpu-set and adds a new rule to
allow system server to set them.

Bug: 274530433
Test: Locally added some code to set those properties and saw it being
  successfull.
Change-Id: Ie28602e9039b7647656594ce5c184d29778fa089
diff --git a/microdroid/system/private/property.te b/microdroid/system/private/property.te
index 638b246..3077301 100644
--- a/microdroid/system/private/property.te
+++ b/microdroid/system/private/property.te
@@ -2,6 +2,7 @@
 
 # Declare ART properties for CompOS
 system_public_prop(dalvik_config_prop)
+system_public_prop(dalvik_dynamic_config_prop)
 system_restricted_prop(device_config_runtime_native_prop)
 system_restricted_prop(device_config_runtime_native_boot_prop)