The compose now contains multiple image builds, but Weldr API does not
support this feature. Use the first image build every time.
Also start using the new types instead of plain strings.
When a use defines the image size for a compose this size is stored in
the compose struct so that the virtual image size can be returned by the
api instead of the file size of the image.
As a part of f4991cb1 ComposeEntry struct was removed from store package.
This change made sense because this struct is connected more with API than
with store - store uses its own Compose struct. In addition, converters
between Compose and ComposeEntry were added. Unfortunately, ComposeEntry
contains ImageSize which was not stored in Compose but retrieved from store
using GetImage method. This made those converters dependent on the store,
which was messy.
To solve this issue this commit adds image struct into Compose struct.
The content of image struct is generated on the worker side - when the worker
sets the compose status to FINISHED, it also sends Image struct with detailed
information about the result.
This commit introduces basic support for upload API. Currently, all the routes
required by cockpit-composer are supported (except for /compose/log).
Also, ComposeEntry struct is moved outside of the store package. I decided
to do it because it isn't connected in any way to store, it's more connected
to API. Due to this move there's currently a known bug that image size is
not returned. This should be solved by moving Image struct inside Compose
struct by follow-up PR.
