"primary" parameter doesn't work

[Julian-Webb]

Describe the bug
When you use the primary flag, which should tell the GroupedListView to use the PrimaryScrollController, you get the following error:

This happens even when you don't specify your own ScrollController. I think this happens because on line 245 in your source code you assign _controller = widget.controller ?? ScrollController(); but instead of creating a new ScrollController, you would need to access the PrimaryScrollController.of(context)

Expected behavior
The GroupedListView should use the PrimaryScrollController when primary: true.

Information:

• Dart version: 3.2.0
• Flutter version: 3.16.0
• Platform: macOS Sonoma 14.2.1 / iPhone 15 emulator
• Package version: grouped_list: ^5.1.2