refactor: Refactored project & updated dependencies

[frgfm]

This PR introduces the following modifications:

• updated dependencies after carefully testing them in Docker
• moved dependency specifiers to pyproject.toml (holding the version ranges) so that poetry can lock the production version (putting specific version into a requirements.txt)
• moved subURLS: alert_screen --> minimal, dashboard_screen --> device_status
• added a user warning for 404 errors
• added Sentry integration through Flask
• reorganized project hierarchy (cf. below)
• removed legacy section from README
• removes cameras.csv & historic_fires.csv
• updated headers & header verification job

The new project organization is as follows:

app
├── assets
│   ├── css
│   │   └── styles.css
│   ├── data
│   │   └── group_correspondences.json
│   └── images
│       ├── background.png
│       ├── favicon.ico
│       ├── pyro_alert_icon.png
│       ├── pyro_alert_off.png
│       ├── pyro_alert_on.png
│       ├── pyro_fire_logo.png
│       ├── pyro_oldfire_icon.png
│       ├── pyro_site_icon.png
│       └── up_arrow_png.png
├── components
│   └── navbar.py
├── config.py
├── main.py
├── pages
│   ├── device_status.py
│   ├── homepage.py
│   ├── risks.py
│   └── screen.py
├── services
│   ├── api.py
│   └── __init__.py
└── utils
    ├── alerts.py
    └── _utils.py

The folders & files are:

• assets: all the static files
• components: html/dsh components used to build pages
• config.py: same as before
• main.py: same as before
• pages: 1 file per app page
• services: same as before
• utils: other functions

One thing that will be left to do is reduce the size of main (moving callbacks or creating subfunctions of utils) because it's way too massive.

Closes #35 Closes #80

Any feedback is welcome!

[frgfm]

Deployed on Heroku, everything seems to be running smoothly :+1:

[frgfm]

ping @Akilditu

[pechouc]

I have checked the changes since the last comments and everything looks good to me. I have also tried to run the app locally after a few changes to prepare another PR and it seemed to work smoothly. I haven't gone into the details and we might want to wait for @Akilditu's green light but, that being said, I am happy to approve the changes if you wish to move forward quickly.