Release stax Application Template bundled

Description of feature

Added two CICD steps to be run when a tag is set:

• Packing : Create an Application Template .zip easily installable by Blender
• Release : Release the .zip as an item to DL.

How to test it

https://gitlab.com/Tilix4/stax/-/releases

And read the docs: https://superprod.gitlab.io/-/stax_suite/stax/-/jobs/1046322893/artifacts/docs/build/html/getting_started.html#installation

Checklist

Please check if your MR fulfills the following requirements:

• Unit tests have been added, if possible
• Documentation has been updated
• Build was run locally and any changes were pushed
• Lint has passed locally without error
• CHANGELOG.md has been updated

FYI: @olivier.hoareau