Currently, Terraform will only run properly signed versions of the experimental
cloud plugin that were downloaded from a TFC instance that provides the
appropriate service. That obstructs development on new cloud plugin features!
Our internal teams will need a "dev override" capability, like what we offer
provider authors.
However, unlike with providers, we don't have to integrate this into a
heterogeneous mix of sources for mirroring and caching a wide range of binaries.
There's only one cloud plugin, HashiCorp controls it, and end users should never
need to override the location of the binary for non-development reasons.
Thus, we have the luxury of being quite a bit stupider in how we handle the
override signal. Instead of adding it to the CLI config file schema, we'll just
use a single environment variable whose value is the path to an alternate
binary.
Enter: `TF_CLOUD_PLUGIN_DEV_OVERRIDE`.
