Move ExactCalculator to androidx.

Bug: 76692459
Test: make -j ExactCalculator and run on emulator
Change-Id: I6d52a233696d41d43fdaabf6863f359c79e4b4f7
diff --git a/src/com/android/calculator2/Calculator.java b/src/com/android/calculator2/Calculator.java
index b3d79eb..392447c 100644
--- a/src/com/android/calculator2/Calculator.java
+++ b/src/com/android/calculator2/Calculator.java
@@ -44,10 +44,10 @@
 import android.graphics.Rect;
 import android.net.Uri;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.StringRes;
-import android.support.v4.content.ContextCompat;
-import android.support.v4.view.ViewPager;
+import androidx.annotation.NonNull;
+import androidx.annotation.StringRes;
+import androidx.core.content.ContextCompat;
+import androidx.viewpager.widget.ViewPager;
 import android.text.Editable;
 import android.text.SpannableStringBuilder;
 import android.text.Spanned;