To allow us to migrate incrementally to terraform-plugin-framework, we need to:

- Run a protocol v5 => v6 translator; and
- Mux SDKv2 and framework servers to serve a unified provider

This gets us moving down that path in to run them in a compatible fashion.

Creates a `consts` package to hold the provider schema that will be shared
between SDKv2 and the plugin framework to prevent typos and duplication.

Copies over the sdkv2 client configuration to make the provider operate 1:1
regardless of the mechanism used.

Right now, there isn't a way to do automatic description decoration based on the
schema attributes[1]. This is a problem because to mux two provider types they
must return identical schemas.

To work around this, I've added conditionals to the generator to ignore the
schema fields in the providers where we may experience differences between the
providers but it remains for all resources and data sources. For now, this
strikes the balance of unblocking us and keeping the documentation nicely
decorated.

[1]: hashicorp/terraform-plugin-framework#625

…nstants