Distinguish identity views from single-target views (backport #4186)

[mergify]

This is a minor overhaul of DataViews internals that make the various use cases of what were previously referred to as "1-1 views" more clear. This incidentally fixes an issue with bulk connections and views.

While for users this is just a bug fix, this has larger implications for developers. This replaces reifySingleData with two more precise functions:

• reifyIdentityView - Fast, used for things like Probe legality (which by having pointer semantics, only really works with identity views).
• reifySingleTarget - Slow, used for legacy annotation support which was, and remains, iffy for views.

A subtle but critical aspect of this PR is that reifyIdentityView works in cases when the reifySingleData did not. It is properly hierarchical: e.g. if you have an Aggregate that is a child of a non-identity view parent yet the child itself is an identity view, it will return the target for that child. This is critical for use cases like FlatIO where the parent Bundle isn't an identity but every single child is.

One negative of this PR is that it makes the awkward "unnamed rename map" logic slower. I benchmarked this on a large design (that uses lots of views) and it's such a small piece of the overall runtime that it's okay (~1%). Regardless that logic is ludicrously slow and is a complete waste. I am thinking about ways to get rid of it but this PR has scope creeped enough. I think we just have to change the annotation API so it's really about coming up with the best way to do it.

This PR actually fixes several bugs, I will file them separately as they illustrate all of the weird corner cases this PR cleans up.

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?
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• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Bugfix

Desired Merge Strategy

• Squash

Release Notes

Fixes #4185, Fixes #4187

Reviewer Checklist (only modified by reviewer)

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This is an automatic backport of pull request #4186 done by [Mergify](https://mergify.com).