move config to `tool.render-engine.cli`

[kjaymiller]

Most third party configurations are listed under the tool

Currently render-engine is at the root with build-system and project.

Should we move this to tool

[kjaymiller]

Linters also get confused by this at root

[brass75]

We need to open an issue for the cookiecutter as well so we don't create sites with invalid configs.

[kjaymiller]

We need to open an issue for the cookiecutter as well so we don't create sites with invalid configs.

Created - render-engine/cookiecutter-render-engine-site#27