Channel interface

Work in Progress

This part of the ecosystem is not standardized yet.

Some preliminary information can be found at:

• https://docs.conda.io/projects/conda-build/en/stable/resources/package-spec.html#repository-structure-and-index
• https://docs.conda.io/projects/conda-build/en/stable/concepts/generating-index.html
• https://github.com/conda/ceps/pull/135