Move import/export to its own module (#6986)

Also clean up ImportExportPreferencesFragment a bit.

app/build.gradle

@@ -86,6 +86,7 @@ dependencies {
     implementation project(':playback:base')
     implementation project(':playback:cast')
     implementation project(':storage:database')
+    implementation project(':storage:importexport')
     implementation project(':storage:preferences')
     implementation project(':ui:app-start-intent')
     implementation project(':ui:common')

app/src/androidTest/java/de/test/antennapod/util/syndication/feedgenerator/Rss2Generator.java

@@ -6,13 +6,15 @@
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.text.SimpleDateFormat;
 import java.util.ArrayList;
+import java.util.Date;
+import java.util.Locale;
 
 import de.danoeh.antennapod.model.feed.Feed;
 import de.danoeh.antennapod.model.feed.FeedFunding;
 import de.danoeh.antennapod.model.feed.FeedItem;
 import de.danoeh.antennapod.parser.feed.namespace.PodcastIndex;
-import de.danoeh.antennapod.core.util.DateFormatter;
 
 /**
  * Creates RSS 2.0 feeds. See FeedGenerator for more information.
@@ -98,7 +100,7 @@ public void writeFeed(Feed feed, OutputStream outputStream, String encoding, lon
                 }
                 if (item.getPubDate() != null) {
                     xml.startTag(null, "pubDate");
-                    xml.text(DateFormatter.formatRfc822Date(item.getPubDate()));
+                    xml.text(formatRfc822Date(item.getPubDate()));
                     xml.endTag(null, "pubDate");
                 }
                 if ((flags & FEATURE_WRITE_GUID) != 0) {
@@ -132,4 +134,9 @@ public void writeFeed(Feed feed, OutputStream outputStream, String encoding, lon
 
         xml.endDocument();
     }
+
+    private static String formatRfc822Date(Date date) {
+        SimpleDateFormat format = new SimpleDateFormat("dd MMM yy HH:mm:ss Z", Locale.US);
+        return format.format(date);
+    }
 }

app/src/main/java/de/danoeh/antennapod/activity/OpmlImportActivity.java

@@ -26,14 +26,14 @@
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.app.ActivityCompat;
 import de.danoeh.antennapod.R;
-import de.danoeh.antennapod.core.export.opml.OpmlElement;
-import de.danoeh.antennapod.core.export.opml.OpmlReader;
 import de.danoeh.antennapod.core.preferences.ThemeSwitcher;
 
 import de.danoeh.antennapod.core.storage.DBTasks;
 import de.danoeh.antennapod.core.util.download.FeedUpdateManager;
 import de.danoeh.antennapod.databinding.OpmlSelectionBinding;
 import de.danoeh.antennapod.model.feed.Feed;
+import de.danoeh.antennapod.storage.importexport.OpmlElement;
+import de.danoeh.antennapod.storage.importexport.OpmlReader;
 import io.reactivex.Completable;
 import io.reactivex.Observable;
 import io.reactivex.android.schedulers.AndroidSchedulers;