Implement introduction screen.

Fixes #1316.

src/main/java/de/dennisguse/opentracks/introduction/WelcomeFragment.java

@@ -0,0 +1,37 @@
+package de.dennisguse.opentracks.introduction;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+
+import de.dennisguse.opentracks.databinding.WelcomeBinding;
+
+public class WelcomeFragment extends Fragment {
+
+    public static WelcomeFragment newInstance() {
+        return new WelcomeFragment();
+    }
+
+    private WelcomeBinding viewBinding;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+    }
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        viewBinding = WelcomeBinding.inflate(inflater, container, false);
+        return viewBinding.getRoot();
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        viewBinding = null;
+    }
+}