redact information when rendering inline functions that may contain secrets

[rabbah]

the viz for a composition that uses let will show the value partially redacted... i suggest an annotation that redacts all of the information and possibly replaces it with a <secret> token instead.

this might requires annotations generated from the composer.

@kerryspchang @tardieu

[starpit]

it seems like a nice feature request to expose the platform secret store, e.g. kubernetes secrets https://kubernetes.io/docs/concepts/configuration/secret/

perhaps composer.secret() @tardieu ?

[starpit]

@rabbah the latest composer no longer shows let values in the value, only on tooltips. is this sufficient to close this issue? i am guessing that the main issue was that screenshots would contain secrets?

having a more rigorous connection to secret stores is also important, but perhaps this is a separate (in particular not a UI) issue?