[PP-1] Parse recipe packages and make available on localization server

Problem/Motivation

The d.o connector does not receive recipes currently, but also l10n_server is not quite capable to tell apart recipes from other general projects. So it needs to be able to identify projects that are not modules or themes but recipes and parse them.

Postponed on ✨ Extract strings from Recipes Active .

Steps to reproduce

Proposed resolution

1. Requires changes in l10n_server to handle general projects and identify which of those are recipes (based on composer.yml).
2. Requires a d.o change outside of l10n_server to export those in the releases.tsv we use in l10n_server's REST connector.
3 Profit!

Remaining tasks

User interface changes

API changes

Data model changes