An environment source collects a dictionary of environment variables values into a hierarchical
config Value type. We have to be aware how the config tree is created from the environment
dictionary, therefore we are mindful about prefixes for the environment keys, level separators,
encoding form (kebab, snake case) etc.
Wrapper type for values that contains secrets, which attempts to limit
accidental exposure and ensure secrets are wiped from memory when dropped.
(e.g. passwords, cryptographic keys, access tokens or other credentials)