Sailjail

Certain files and directories are protected on SailfishOS. This was done on < 4.0 using privileges (see !122 (merged)), and since 4.0 there's the experimental SailJail. I previously believed that we needed this, but the privileges system work perfectly fine. This MR serves as a demo of SailJail for WF.

Implements #400 (closed)

• Rebase when !122 (merged) is merged

Sailfish 3.4 compatibility

~~This is the main issue. To enter the jail, we need to launch Whisperfish through /usr/bin/sailjail, which doesn't exist on 3.4. I see two options here: either the SailfishOS 3.4 community provides some sailjail-compat package, that just executes the arguments to /usr/bin/sailjail without actually jailing anything, or we provide two different Whisperfish versions that ship different .desktop files depending on < 3.4 vs >= 4.0. We can also (but holy 💩 that's ugly) make harbour-whisperfish a script that decides on whether to jail itself or not.

• Decide on the compat strategy -> We go with a shell script for now, maybe transpose that into separate builds some day later.
• Implement the compat strategy~~

Jolla did this for us in 4.4, hooray!

Jailing

• Add the necessary permissions to the .desktop file
  • Still needs something to access pictures/gallery for sending attachments.
• Start Whisperfish jailed
• Remove privileges after !122 (merged) is merged (revert 96095c00)
• If still relevant, make sure translatables for the custom permission(s) are there.
• Figure out what happened to notifications.

Fix #400 (closed) #232 (closed) #231 (closed) #132 (closed)

/post_ci_links