Add GitHub Workflow for building Sengi

[joschi]

This pull request adds a GitHub workflow for building the Sengi web application, deploy it to https://sengiapp.github.io/ (GitHub Pages), and in case it was triggered by a new tag, it will create a draft release for this tag and attach a ZIP archive of the Sengi web application built from the tagged commit.

I took the liberty to create the SengiApp organization on GitHub in order to test the automatic deployment via the GitHub workflow. I've invited @NicolasConstant as an owner to the organization and will leave it afterwards.

Example workflow run for a regular commit (with automatic deployment):
https://github.com/joschi/sengi/actions/runs/587208773

Example workflow run for a tag (with automatic upload of the Sengi web application to the draft release):
https://github.com/joschi/sengi/actions/runs/587209190

Example draft release created by the workflow:

Closes #353

[NicolasConstant]

Thanks, it's a really interesting illustration but unfortunately I don't plan to add new CICD pipelines to the currents ones (I already have Travis and AppVeyor set-up and if I would put my hands in CICD it would be to reduce them to a single one and not adding more to the stack).

AppVeyor is the legacy one and I had to add Travis because at that time they were the only one to provide MacOS (for MacOS builds), now that AppVeyor is also supporting MacOS we could look to migrate all of CICD pipelines to one of them.

[joschi]

AppVeyor is the legacy one and I had to add Travis because at that time they were the only one to provide MacOS (for MacOS builds), now that AppVeyor is also supporting MacOS we could look to migrate all of CICD pipelines to one of them.

GitHub Actions supports Linux (via Ubuntu), macOS, and Windows too.

If you think it's worth a shot, I can try coming up with a proof of concept for using GitHub Actions to build the Electron distributions of Sengi.

[NicolasConstant]

GitHub Actions supports Linux (via Ubuntu), macOS, and Windows too.

Oh I wasn't aware it was already supporting it.

Currently we have this CICD strategy:

• AppVeyor builds the web version and publish it on a remote web server via FTP (we can't change this for a Github page or anything else since current clients rely on it)
• Travis builds the electron builds (Win, MacOS, Linux)

Since I will not change the hosting of the official instance to prevent breaking things, the only advantage to migrate all those pipelines to a Github one would be to fix #353, that could also be achieved by looking to perform this action with either Travis or AppVeyor.

Maybe it would take less time to enhance existing CICD pipelines, but if you manage to have all those constraints in Github Actions I will have a serious look at it and will consider to replace current CICD pipelines by it.