rbt land --json now includes information on whether the change was

approved (helping to differentiate approval failures from other

failures), as well as including information on the review request that

failed approval.
When successful, the payloads for each landed review request now always

has a type key (which will be patch when applying a review request

via an ID), and will always contain a source_branch (which defaults to

null). This creates consistency in the payload.

Tested landing approved changes.
Tested attempting to land unapproved changes.
Tested attempting to land changes and hitting (manufactured) errors.
In all cases, I saw the output I expected.