Generate manifest with the contents of the project

Issue Context

It would be nice to generate a manifest files with the contents of the different runtimes, so people doesnt have to inspect the bst files directly

Issue Description

Generate a file with at least this info:

• Component
• Version

Open a issue in buildstream to generate this, see: BuildStream/buildstream#235 (closed)

Acceptance Criteria

A manifest should be generated, probably as output of the CI