They are executed when building the "builder" image, those are not accounted to the diffs when producing the final artifact
Reuse the Recipe and extend it to read a separate tree for build dependencies. Also add accessors to compilespec to produce dockerfile image format.
Create compiler interface with switchable backends. For now it can resolve and parse a `build.yaml` which is in the same folder as in `definition.yaml` Add also tests to cover this and new fixtures
