Fix InputDecorators suffix and prefix widgets are tappable when hidden

[TahaTesser]

fixes The InputDecoration's suffix and prefix widget can be tapped even if it does not appear

This PR also updates two existing tests to pass the tests for this PR. These tests are trying to tap prefix and suffix widgets when they're hidden. While the linked issue had visible prefix and suffix widgets #39376 for reproduction.

Code sample

expand to view the code sample

import 'package:flutter/material.dart';

void main() {
  runApp(MainApp());
}

class MainApp extends StatelessWidget {
  final _messangerKey = GlobalKey<ScaffoldMessengerState>();

  MainApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      scaffoldMessengerKey: _messangerKey,
      home: Scaffold(
        body: Container(
          alignment: Alignment.center,
          padding: const EdgeInsets.all(16.0),
          child: TextField(
            decoration: InputDecoration(
              labelText: 'Something',
              prefix: GestureDetector(
                onTap: () {
                  _messangerKey.currentState?.showSnackBar(
                      const SnackBar(content: Text('A tap has occurred')));
                },
                child: const Icon(Icons.search),
              ),
              suffix: GestureDetector(
                onTap: () {
                  _messangerKey.currentState?.showSnackBar(
                      const SnackBar(content: Text('A tap has occurred')));
                },
                child: const Icon(Icons.search),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

Before

After

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[bleroux]

LGTM!