Tropy Flatpak

Permissions rationale

Tropy requests the following restricted permissions: - Filesystem: we use access to home /media and /run/media because Tropy needs access to all files in a Tropy project. - Wayland: since 1.16 we use --socket=wayland and --socket=fallback-x11 - Network: we use --share=network because Tropy needs to fetch remote images if you import them by pasting a URL. - WebGL: --device=dri is required becuase Tropy's image viewer needs access to the GPU.

Update sources notes

- Fetch and unpack the Tropy sources outside of the sandbox
- Run `flatpak-node-generator --electron-node-headers --electron-ffmpeg=lib npm package-lock.json`
- Fix node-gyp cache install version from 9 to 11
- Fix electron cache link to SHASUMS256.txt