Fix qt crash

[Cimbali]

This PR fixes #500 by:

• adding the import that defines ColorImage (an undocumented QtQuick internal) to the files that use it. The better fix would be to use a documented way of displaying images, but this is the simplest fix.
• Renames popupType to popupPrio as it is used for priority of popups, and because popupType is a (final) property of QtQuick popups since 6.8

Note that:

• Fixes are trivial
• Any platforms running Qt 6.8 are affected, so not Arch-specific as claimed in Fails to start with Qt 6.8 #500 (neither OpenSUSE-specific, Ubuntu non-LTS, Fedora 41, Fedora Rawhide, etc. etc. -- all up-to-date platforms are affected by the bug, the others will be in time when updating Qt)
• Qt 6.8 is marked as LTS so there is even more value in fixing this early on
• Seen the dismissive answers on Fails to start with Qt 6.8 #500 😢, I share this more for package maintainers and self-builders than hoping it will get merged. Feel free to use these patches until upstream provides their own fixes.

[Antiz96]

@Cimbali Thanks a lot!

I can confirm these patches work as intended (tested on Arch Linux). I backported them to the Arch's protonmail-bridge package while waiting for them to be merged & released here (or for upstream to provide their own fixes at some point).

[joekm]

Thanks for the patch. Also felt bad for the developers getting all that whining from a few Arch users over such a trivial matter. I. E. - just run it without the QT interface until 6.8 becomes more commonplace. This kind of thing is "par for the course" for Arch (or any distro close to "bleeding edge"), and the Proton developers had an easy work around already in place.