[WifiSettings] Add Wi-Fi dialog activity

Add a Wi-Fi dialog activity that can be started by setup wizard to
connect to a Wi-Fi access point.

Also refactored mEdit and mModify in WifiConfigController into an
int-enum mMode, with modes view, connect and modify. This is how the
new modes maps to the old flags:

MODE_VIEW     --  mEdit = false, mModify = *
MODE_CONNECT  --  mEdit = true, mModify = false
MODE_MODIFY   --  mEdit = true, mModify = true

Bug: 23426311
Change-Id: I8e2221fd3c42577068e07686dab245dd5888e0ae
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index b648744..0e5bc97 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -2500,6 +2500,16 @@
             android:excludeFromRecents="true">
         </activity>
 
+        <activity android:name=".wifi.WifiDialogActivity"
+            android:theme="@style/Transparent"
+            android:excludeFromRecents="true"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="com.android.settings.WIFI_DIALOG" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </activity>
+
         <activity android:name=".sim.SimDialogActivity"
                 android:theme="@android:style/Theme.Material.Light.Dialog.NoActionBar"
                 android:label="@string/sim_settings_title"