In the output test, check that for a successful pipeline run all
the elements are present: main result, assembler result, stage
result.
NB: Build result is hard to test because we would need to actually
build a valid build root.
Instead of using `org.osbuild.test` stages, so `org.osbuild.noop`
stages so that the options we pass are actually valid and we can
use the manifest in schema validation checking.
Convert the assembler phase of the main pipeline in the old format
into a new Pipeline that as the assembler as a stage, where the
input of that stage is the main pipeline. This removes the need of
having "assemblers" as special concepts and thus the corresponding
code in `Pipeline` is removed. The new assembler pipeline is marked
as exported, but the pipeline that builds the tree is not anymore.
Adapt the `describe` and `output` functions of the `v1` format to
handle the assembler pipeline. Also change the tests accordingly.
NB: The id reported for the assembler via `--inspect` and the result
will change as a result of this, since the assembler stage is now
the first and only stage of a new pipeline and thus has no base
anymore.
Every pipeline that gets added to the `Manifest` now need to have
a unique name by which it can be identified. The version 1 format
loader is changed so that the main pipeline that builds the tree
is always called `tree`. The build pipeline for it will be called
`build` and further recursive build pipelines `build-build`, where
the number of repetitions of `build` corresponds to their level of
nesting. An assembler, if it exists, will be added as `assembler`.
The `Manifest.__getitem__` helper is changed so it will first try
to access pipeline via its name and then fall back to an id based
search. NB: in the degenrate case of multiple pipelines that have
exactly the same `id`, i.e. same stages, with the same options and
same build pipeline, only the first one will be return; but only
the first one here will be built as well, so this is in practice
not a problem.
The formatter uses this helper to get the tree pipeline via its
name wherever it is needed.
This also adds an `__iter__` method `Manifest` to ease iterating
over just the pipeline values, a la `for pipeline in manifet`.
The current description test took a hand crafted Manifest. Since
the internal `Manifest` representation and the format (version 1)
representation are becoming more and more different, it might
soon not be possible to go from `Manifest` to the format specific
description unless it was previously loaded and thus an internal
mapping table can aid the serialization. Thus the description
test is re-worked to load a manifest and then describe it and
compare that the result is the same.
Also rename the test from `test_pipeline` to `test_describe`
as this is a better description of the test.
