[Add] 커뮤니티 로딩 화면 추가

app/src/main/res/layout/dialog_loading.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@color/white"
+    android:gravity="center">
+
+    <ProgressBar
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:indeterminate="true"
+    android:layout_centerInParent="true" />
+
+</RelativeLayout>