Allow to create projects from CLI

[Raruto]

Closes: #434

How to use

Refresh all demo projects (git pull from: g3w-suite-demo-projects):

python3 manage.py reload_demo

Upload a specific project:

python3 manage.py load_project --file=/path/to/your/projects/demo.qgs --data=/path/to/your/projects_data/

Fallbacks to g3w-suite-demo-projects/projects/demo.qgs when not found locally:

python3 manage.py load_project --file=demo.qgs

NB: organization of data and projects

Local QGIS projects "should" be organized in compliance with the following folder structure:

[Raruto]

@wlorenzetti is it okay?

It would be great if you could include a sample django test:

• https://adamj.eu/tech/2020/09/07/how-to-unit-test-a-django-management-command/
• https://docs.djangoproject.com/en/3.2/topics/testing/tools/#topics-testing-management-commands

[wlorenzetti]

@wlorenzetti is it okay?

I'll try very soon