Add "Where is my NFC reader?" feature to nfc waiting dialog

OpenKeychain/src/main/res/values/strings.xml

@@ -1961,4 +1961,6 @@
         <item quantity="other">"Updating %d keys"</item>
     </plurals>
 
+    <string name="button_locate_nfc">"Where is my NFC reader?"</string>
+
 </resources>

OpenKeychain/src/main/res/values/themes.xml

@@ -133,5 +133,18 @@
         <item name="windowNoTitle">true</item>
     </style>
 
+    <style name="Theme.Keychain.AppCompat.Transparent" parent="Theme.AppCompat.NoActionBar">
+        <item name="android:windowNoTitle">true</item>
+        <item name="android:windowBackground">@android:color/transparent</item>
+        <item name="android:colorBackgroundCacheHint">@null</item>
+        <item name="android:windowIsTranslucent">true</item>
+        <item name="android:windowFullscreen">true</item>
+        <item name="android:windowAnimationStyle">@style/Animation.AppCompat.Dialog</item>
+    </style>
+
+    <style name="Theme.Keychain.AppCompat.Transparent.Fullscreen" parent="Theme.Keychain.AppCompat.Transparent">
+        <item name="android:windowFullscreen">true</item>
+    </style>
+
     <style name="Theme.Keychain.Transparent" parent="@android:style/Theme.NoDisplay" />
 </resources>