Since we're hardening what Packer is able to load locally when it comes
to plugins, we need also to harden the installation process a bit.
While testing we noticed some remotes had published their plugins with
version mismatches between the tag and the binary.
This was not a problem in the past, as Packer did not care for this,
only the binary name was important, and the plugin could be installed
without problem.
Nowadays however, since Packer enforces the plugin version reported in
the name to be the same as the plugin self-reported version, this makes
it impossible for the installed plugin to load anymore in such an
instance.
Therefore in order to limit confusion, and so users are able to
understand the problem and report it to the plugins with that mismatch,
we instead install the plugin as a dev version, and report it to the
user so they can still use it, but are able to report it to the plugin
developers.