Add Keystore migration method to WifiMigration.

Bug: 332560152
Flag: android.net.wifi.flags.legacy_keystore_to_wifi_blobstore_migration
Test: atest WifiMigrationTest
Change-Id: I2ee61f765c8a1922563fa1242d6ce838a0a22863
diff --git a/wifi/wifi.aconfig b/wifi/wifi.aconfig
index c5bc039..c1effe1 100644
--- a/wifi/wifi.aconfig
+++ b/wifi/wifi.aconfig
@@ -17,3 +17,11 @@
     description: "Control the API that allows setting / reading the NetworkProviderInfo's battery charging status"
     bug: "305067231"
 }
+
+flag {
+    name: "legacy_keystore_to_wifi_blobstore_migration"
+    is_exported: true
+    namespace: "wifi"
+    description: "Add API to migrate all values from Legacy Keystore to the new Wifi Blobstore database"
+    bug: "332560152"
+}