ProfileList: Add minimal activity

For now, it simply reads the files in the app's data directory with
file names ending in ".conf" and displays them in a list.

This includes the generic list data binding setup for future use.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/AndroidManifest.xml

@@ -9,6 +9,13 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@android:style/Theme.Material.Light.DarkActionBar">
+        <activity android:name=".ProfileListActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
     </application>
 
 </manifest>