feat(ui): added backgroundColor property to GalleryFooter

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat_flutter/lib/src/gallery_footer.dart

@@ -27,6 +27,7 @@ class GalleryFooter extends StatefulWidget implements PreferredSizeWidget {
     this.totalPages = 0,
     this.mediaAttachments = const [],
     this.mediaSelectedCallBack,
+    this.backgroundColor,
   })  : preferredSize = const Size.fromHeight(kToolbarHeight),
         super(key: key);
 
@@ -55,6 +56,9 @@ class GalleryFooter extends StatefulWidget implements PreferredSizeWidget {
   /// Callback when media is selected
   final ValueChanged<int>? mediaSelectedCallBack;
 
+  /// The background color of this [GalleryFooter].
+  final Color? backgroundColor;
+
   @override
   _GalleryFooterState createState() => _GalleryFooterState();
 
@@ -90,7 +94,8 @@ class _GalleryFooterState extends State<GalleryFooter> {
         context: context,
         removeTop: true,
         child: BottomAppBar(
-          color: galleryFooterThemeData.backgroundColor,
+          color:
+              widget.backgroundColor ?? galleryFooterThemeData.backgroundColor,
           child: Row(
             mainAxisAlignment: MainAxisAlignment.spaceBetween,
             children: [