When a provider does not natively understand secrets, we need to pass
inputs as raw values, as to not confuse it.
This leads to a not great experience by default, where we pass raw
values to `Check` and then use the results as the inputs to remaining
operations. This means that by default, we don't end up retaining
information about secrets in the checkpoint, since the call to `Check`
erases all of our information about secrets.
To provide a nicer experience we were don't lose information about
secrets even in cases where providers don't natively understand them,
we take property maps produced by the provider and mark any values in
them that are not listed as secret as secret if the coresponding input
was a secret.
This ensures that any secret property values in the inputs are
reflected back into the outputs, even for providers that don't
understand secrets natively.
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