Fix AppData XML to make it pass validation

refactor: replace QString constructors with QStringLiteral

Fix image copying on windows

Fix room settings and emoji verification being cut off

- The translation key needs the .qm files to be included to work (so it's useless right now; the CMake
script needs to be adjusted to install those files and make this key work properly)
- The Purism custom keys don't seem to be relevant anymore (so that's another useless thing)
- The donation key needs an URL to be useful (the FIXME is still left so it can be readded later)

This time also generate the pri files, whatever they are.

See https://learn.microsoft.com/en-us/windows/msix/desktop/desktop-to-uwp-manual-conversion#optional-add-target-based-unplated-assets

There is no use case for those afaik and they do break our replacement
in the frontend. Let's instead strip them out in the sanitization step,
since there are no valid attributes defined for the del tag currenlty.

In theory we could also strip out all attributes here, but that seems
excessive for now.

Fixes https://github.com/Nheko-Reborn/nheko/issues/1693

fixes #1699

Remove reference to unmaintained AUR helper

See https://bugreports.qt.io/browse/QTBUG-102078

https://github.com/rmarquis/pacaur is long unmaintained.

Update README.md to reflect the keyring use flag for qtkeychain

Currently translated at 51.0% (534 of 1047 strings)

Co-authored-by: Tmpod <tom@tmpod.dev>
Co-authored-by: Weblate <noreply@weblate.org>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/pt_PT/
Translation: Nheko/nheko

Currently translated at 85.2% (893 of 1047 strings)

Translated using Weblate (Polish)

Currently translated at 85.2% (893 of 1047 strings)

Co-authored-by: Przemysław Romanik <github@rom4nik.pl>
Co-authored-by: Weblate <noreply@weblate.org>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/pl/
Translation: Nheko/nheko

Currently translated at 100.0% (1047 of 1047 strings)

Translated using Weblate (Dutch)

Currently translated at 100.0% (1047 of 1047 strings)

Translated using Weblate (Dutch)

Currently translated at 93.2% (976 of 1047 strings)

Co-authored-by: Jaron Viëtor <jaron@v8or.nl>
Co-authored-by: Ruben De Smet <ruben.de.smet@rubdos.be>
Co-authored-by: Weblate <noreply@weblate.org>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/nl/
Translation: Nheko/nheko

Currently translated at 19.6% (206 of 1047 strings)

Co-authored-by: Tennouji Misaki <TennoujiMisaki@users.noreply.weblate.nheko.im>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/tr/
Translation: Nheko/nheko