Friendlier wrapper for `transform.foreach`.
To facilitate that friendliness, makes it so that `OpResult.owner`
returns the relevant `OpView` instead of `Operation`. For good measure,
also changes `Value.owner` to return `OpView` instead of `Operation`,
thereby ensuring consistency. That is, makes it is so that all
op-returning `.owner` accessors return `OpView` (and thereby give access
to all goodies available on registered `OpView`s.)
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