Right-click menu for non-field types

[philrz]

Repro is with Zui commit e8a538e.

While reviewing #3145, I became hip to the fact that the right-click menu currently only seems to activate on named field/value pairs in records. For instance, in the attached video, I drag the test data primitive.zson.gz into the app with intent to right-click and select New Search With This Value, but it does not appear. I can make it appear if I yield the primitive values in a record expression, but this is surely not something we want to ask of users.

https://github.com/user-attachments/assets/a2a5d877-e32a-4a4e-8ca9-d2b06e1fcc99

As @jameskerr remarked upon discussing this:

Yes, let's get a menu for non-field types.