Materialize wires for .ref of Aggregate views (backport #4080)

[mergify]

Fixes #4079. This will result in some wires that may not be necessary which is particularly inelegant for Probes, but it makes certain things work that didn't use to and can be improved further as necessary.

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Bugfix

Desired Merge Strategy

• Squash

Release Notes

Fix muxing and probing of views of Aggregates

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.6.x, 5.x, or 6.x depending on impact, API modification or big change: 7.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash), clean up the commit message, and label with Please Merge.
  • Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.

---

This is an automatic backport of pull request #4080 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 5af27e5 has failed:

On branch mergify/bp/5.x/pr-4080
Your branch is up to date with 'origin/5.x'.

You are currently cherry-picking commit 5af27e5d8.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   core/src/main/scala/chisel3/Data.scala

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/test/scala/chiselTests/experimental/DataView.scala

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: jackkoenig / name: Jack Koenig (1b453b7, 911c8fd)