refactor code to move away from the RenderConfig() usage, and just use fully-written example templates in the test-fixtures folder.
Upgrade tests to use the newer testing framework from the plugin sdk that shells out to packer build instead of creating and running a core. This allows us to upgrade to the version of the SDK that strips out the circular dependency with Packer, once we've released it.
use hcl2_upgrade to create HCL versions of the acceptance tests we already run; and add those files to run in addition to the JSON tests.
packer build
instead of creating and running a core. This allows us to upgrade to the version of the SDK that strips out the circular dependency with Packer, once we've released it.