Handle the highest priority exceptions in the cause chain

[rinmu]

Change to handle the highest priority exception in the exception cause chain.
rescue_from handler that are defined later have higher priority.
The priority does not depend on outside or inside of composition relation by Exception#cause.

Fixes #29739

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[eileencodes]

cc/ @matthewd since you commented on the original issue.

[matthewd]

As I stated in my comment, the change was deliberate.

I also described a change I think we should make. This is not that.

[rinmu]

@matthewd I'm sorry, I seem to misunderstood your comment.
I have understood that the change was intentional.

Does that mean that we should continue to put a patch like @TurtleKitty commented on #29739 in the future?
Or is there a way to solve our problem while keeping the change intention?
Unfortunately I have no idea.
If I got that suggestion, I will change this PR.

[matthewd]

in the specific case of ActionView::Template::Error [..] we do want different something different:

• If the application has explicitly defined a handler for ActionView::Template::Error, that should of course be invoked.
• But otherwise, it should hit a specific handler inside the framework, which will unwrap and focus on the cause.

[rinmu]

Because the change contents are greatly different, I made another PR #30613.