We want to be able to give better information if e.g. the entire module is stored in a local and the deprecated value is only later used.

Where the diag is emitted we might only see the local and not the true origin of the deprecation

A string identifying the source of the deprecation should help

…rtain locations

Mainly terminal locations for the value where they are used, such as the config of a resource, for_each, outputs.
We don't want to evaluate the deprecation deeply when it comes to values where the value is not yet used, e.g. locals
This is because if e.g. a deeply nested value is deprecated it should still be ok for the entire object to be in a local
whereas the same object should give a warning in e.g. an output