Previously we were attempting to infer the checkable object address kind
of a given address by whether it included "output" in the position where
a resource type name would otherwise go.
That was already potentially risky because we've historically not
prevented a resource type named "output", and it's also a
forward-compatibility hazard in case we introduce additional object kinds
with entirely-new addressing schemes in future.
Given that, we'll instead always be explicit about what kind of address
we're storing in a wire or file format, so that we can make sure to always
use the intended parser when reading an address back into memory, or
return an error if we encounter a kind we're not familiar with.
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