Simplify Capact Implementation manifest syntax

[pkosiec]

Description

Current Capact Implementation manifest syntax leave much to be desired. There is much of boilerplate which increases the time for new manifests development. Even if we have generators, we should still think about some simplification.

The main pain point probably is the data transformation - we need to merge inputs and render them using Jinja templating very often, as usually some input to a step is based on output from the previous one.

We need to think about viable solutions. Some loose ideas:

• Some abstraction around Argo workflows syntax (to cover the most common use cases)
  • e.g. over the data merging step / Jinja2 templating
• Completely rethinking our way how we render manifests (maybe we should go step back and refactor rendering to be universal instead of using Argo superset?)
• @mszostok suggested: instead of using Argo output artifacts, maybe we should use output parameters? We need to see if that helps much

Reason

Capact manifests contain a lot of boilerplate, which make building manifests time-consuming and difficult to read.

Use cases

As a Content Developer, I want to create Capact manifests as quickly as possible with minimal overhead.