TODOs for the rendered recipe yaml

[wolfv]

• [x] Should flatten serialization of pin_compatible and pin_subpackage
• [ ] Add sha256 hash to rendered path source (at least for files)
• [ ] Add sha256 hash to patch files
• [x] Rename the recipe to recipe.yaml in the info/recipe folder

Ref: https://github.com/wolfv/ceps/blob/cep-recipe-serialization/cep-recipe-serialization.md