upgrade of Redirect import activity

-> RedirectImportActivity is transparent now
-> some poinlessly data removed
-> String moved into sources
-> xml for activity simplified

OpenKeychain/src/main/AndroidManifest.xml

@@ -718,7 +718,8 @@
         <activity
             android:name=".ui.RedirectImportKeysActivity"
             android:configChanges="orientation|screenSize|keyboardHidden|keyboard"
-            android:label="@string/title_activity_redirect_key">  >
+            android:label="@string/title_activity_redirect_key"
+            android:theme="@android:style/Theme.Translucent">
 
             <!-- VIEW with fingerprint scheme:
                       Handle URIs with fingerprints when scanning directly from Barcode Scanner -->