Add new flag for Tethering w/ SoftApConfig

Old flag gantry flow was disabled due to being out of sync
(b/362407371). This change adds a new version of the same flag to
kickstart a new gantry flow.

Flag: com.android.net.flags.tethering_with_soft_ap_config

Bug: 216524590
Test: build
Change-Id: I50701582852c2077e7807ab2685e390f112fd029
diff --git a/common/flags.aconfig b/common/flags.aconfig
index 4c6d8ba..3496a3f 100644
--- a/common/flags.aconfig
+++ b/common/flags.aconfig
@@ -50,6 +50,15 @@
 }
 
 flag {
+  name: "tethering_with_soft_ap_config"
+  is_exported: true
+  namespace: "android_core_networking"
+  description: "The flag controls the access for the parcelable TetheringRequest with getSoftApConfiguration/setSoftApConfiguration API"
+  bug: "216524590"
+  is_fixed_read_only: true
+}
+
+flag {
   name: "request_restricted_wifi"
   is_exported: true
   namespace: "android_core_networking"