When initializing a configuration which refers to re-namespaced legacy
providers, we attempt to detect this and display a diagnostic message.
Previously this message would direct the user to run the 0.13upgrade
command, but without specifying in which directories.
This commit detects which modules are using the providers in question,
and for local modules displays a list of upgrade commands which specify
the source directories of these modules.
For remote modules, we display a separate list noting that they need to
be upgraded elsewhere, providing both the local module call name and the
module source address.
Fetching a default namespace provider from the public registry can
result in 404 Not Found error. This might be caused by a previously-
default provider moving to a new namespace, which means that the
configuration needs to be upgraded to use an explicit provider source.
This commit adds a more detailed diagnostic for this situation,
suggesting that the intended provider might be in a new namespace. The
recommended course of action is to run the 0.13upgrade command to
generate the correct required_providers configuration.