Revert "共有ビューモデル実装"

This reverts commit 6d17811ada.

component/viewer/src/main/java/one/nem/lacerta/component/viewer/SharedViewModel.java

@@ -1,19 +0,0 @@
-package one.nem.lacerta.component.viewer;
-
-import androidx.lifecycle.MutableLiveData;
-import androidx.lifecycle.ViewModel;
-
-public class SharedViewModel extends ViewModel {
-
-    private final MutableLiveData<Integer> currentFragmentPosition = new MutableLiveData<>();
-
-    public void setCurrentFragmentPosition(int position) {
-        currentFragmentPosition.setValue(position);
-    }
-
-    public int getCurrentFragmentPosition() {
-        assert currentFragmentPosition.getValue() != null;
-        return currentFragmentPosition.getValue();
-    }
-
-}