This applies the updates to PrimaryScrollController to SingleChildScrollView. It was left out in the original PR.

From original PR (#102099) for context:

This updates the PrimaryScrollController to not automatically attach to scroll views on desktop as it does on mobile platforms.
This behavior has caused a lot of issues for users developing desktop applications that have multiple parallel vertical ScrollViews.
This adds two parameters to PrimaryScrollController

• automaticallyInheritForPlatforms
  • specifies a set of TargetPlatforms that will engage automatic inheritance
• scrollDirection
  • This adds the ability to specify which axis the PrimaryScrollController should be inherited for.

Also adds static method shouldInherit, which uses the two properties above to determine if automatically inheriting the ScrollController is appropriate for the current configuration.

This design and other approaches is discussed at length in this design document.

Fixes #100264
Related (among others):

• [WIP] Updating PrimaryScrollController #100388
• PrimaryScrollController attached to multiple scroll views in TabBarView's keep-alive tabs #81152
• pageView ScrollController attached to multiple scroll views. #86549
• ScrollController attached to multiple scroll views #83671
• "ScrollController attached to multiple scroll views" in CupertinoTabScaffold #82846
• ScrollController attached to multiple scroll views Failed assertion: line 109 pos 12: '_positions.length == 1' #80664
• ScrollController attached to multiple scroll views #79443
• <ScrollController attached to multiple scroll views> while navigating to back to a page with scrollController #74372
• ScrollController attached to multiple scroll views #71946
• ScrollController attached to multiple scroll views #71682
• ScrollController attached to multiple scroll views. 'package:flutter/src/widgets/scroll_controller.dart': Failed assertion: line 111 pos 12: '_positions.length == 1' #70764
• PageView + PageView + ListView + viewportFraction -> ScrollController attached to multiple scroll views. #63359

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.

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