Super-productivity: add support for on premise Taiga

[alexanderadam]

Problem Statement

Taiga integration is missing.

:grey_question: Possible Solution

Implement another provider for Taiga.
In case you want to make sure that integration works, you can simply test the API integration on the _official instance_ at https://www.taiga.io/.
You can find the official documentation at taigaio.github.io/taiga-do.
If you rather want to use a _local_ Taiga instance, you might want to use this docker-compose setup or one of the other installations.

:arrow_heading_up: Describe alternatives you've considered

Not using Taiga?

:heavy_plus_sign: Additional context

Thank you for your work! :pray:

[johannesjo]

Hey there thanks for opening this up. Unless demand is huge, I probably won't implement this myself, but I gladly review any PRs.

[sunjam]

Taiga is excellent as a fully open source project management solution with Kanban and Scrum support. It is a nice, open alternative to Jira.

[qubist-pixel-ux]

Taiga is lighter than jira (ram wise).