wifi: Add a new property to indicate active wifi iface

Denial:
libc    : Unable to set property "wifi.active_interface" to "wlan0":
error code: 0x18

Bug: 129506593
Test: Verified that the denial is no longer seen in the logs
Change-Id: Ia345f5df1446e7ba3a44d6e8299bdc1f5f6ad9c8
diff --git a/public/property_contexts b/public/property_contexts
index 3ac4673..5bf95e5 100644
--- a/public/property_contexts
+++ b/public/property_contexts
@@ -343,6 +343,7 @@
 ro.vndk.lite u:object_r:exported_default_prop:s0 exact bool
 ro.vndk.version u:object_r:exported_default_prop:s0 exact string
 ro.vts.coverage u:object_r:exported_default_prop:s0 exact int
+wifi.active.interface u:object_r:exported_wifi_prop:s0 exact string
 wifi.concurrent.interface u:object_r:exported_default_prop:s0 exact string
 wifi.direct.interface u:object_r:exported_default_prop:s0 exact string
 wifi.interface u:object_r:exported_default_prop:s0 exact string