Added ExpansionTileController

[HansMuller]

Supports programmatically expanding or collapsing an ExpansionTile.

Most of the work for this PR was completed by @xvrh in #107038.

Fixes #60387

Here's an example:

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final ExpansionTileController controller = ExpansionTileController();

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        ExpansionTile(
          controller: controller,
          title: const Text('Collapsible menu'),
          children: const <Widget>[
            Text('Menu'),
          ],
        ),
        ElevatedButton(
          onPressed: () {
            if (controller.isExpanded) {
              controller.collapse();
            } else {
              controller.expand();
            }
          },
          child: const Text('TOGGLE MENU'),
        )
      ],
    );
  }
}

[HansMuller]

This PR doesn't include something comparable to ExpansionTile.of(context) from #107038; I will add ExpansionTileController.of(context).

[Piinks]

LGTM! Thank you!

I will add ExpansionTileController.of(context).

Did you want to do that in this PR or in a separate one?

[HansMuller]

I've added ExpansionController.of,maybeOf to this PR. Should be ready for review.

[Piinks]

This is the same sample back to back, is that intended?

[Piinks]

Please pull from remote before adding ore commits. I fixed typos before and now to try to be helpful.

[Piinks]

This is still the same sample back to back, is this intended?

[HansMuller]

Yes. The sample covers both topics.

[Piinks]

Would it make more sense to have it shown once, and discuss the two cases together? Otherwise when you read the first one, half of the code has no context, and then when you read it again the second time it appears, it makes full sense.

[HansMuller]

I see what you mean, yes. Merged the doc.

[hadi7khan]

what about list of ExpansionTile? How to pass different controllers n control expand close for every tile