fix missing header import

Change-Id: I7666a22222d68621bc32ed769959091ba8bbcb52

Author: morganchen12

FirebaseFirestoreUI/FirebaseFirestoreUI.h

@@ -25,3 +25,4 @@ FOUNDATION_EXPORT const unsigned char FirebaseFirestoreUIVersionString[];
 #import <FirebaseFirestoreUI/FUISnapshotArrayDiff.h>
 #import <FirebaseFirestoreUI/FUIBatchedArray.h>
 #import <FirebaseFirestoreUI/FUIFirestoreCollectionViewDataSource.h>
+#import <FirebaseFirestoreUI/FUIFirestoreTableViewDataSource.h>