Property now extends Data, remove BaseType

[jackkoenig]

Currently a draft PR because there is more to do:

• Merge some of the code in Property back into Data
• Rip out BaseType
• Make Bundles and Vecs containing Properties work
• Figure out what to do with connections containing Properties

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

• API modification

A new entry in the Data subhierarchy is a pretty substantial change that will affect users.

Desired Merge Strategy

• Squash

Release Notes

Properties can be fields of Bundles and used in wires.

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: 3.5.x, 3.6.x, or 5.x depending on impact, API modification or big change: 6.0)?
• 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.

[jackkoenig]

Note that I carefully reconstructed the order of fields in Data from before BaseType was added (and took some of the fields out in #3429), you can diff Data.scala with the prior commit (878733f) to see.

[seldridge]

LGTM

Do I read this correctly in that this is working for Wire, too?

[jackkoenig]

Do I read this correctly in that this is working for Wire, too?

You do indeed, I'll mention that in the release notes.