For GCC/Clang that is the default, but not for MSVC. This can cause both
compile-time and runtime errors when encountering string literals that
contain more than just 7bit ASCII.

Some of our modules set this already, others use various other workarounds
to avoid Utf-8 literals, so better do this consistently and centrally.
Qt6 will also set this by default.

This is actually Hannah's finding from debugging issues caused by this
in kitinerary, I'm just submitting the patch.

Before this value was 240, which can result in excessively long lines.

It is based on the one that can be found in KWin.

Several KDE projects already use libepoxy (KWin and KDeclarative).

This adds support for image assets not represented in the appstream data,
such as the banner image for the F-Droid app, and it allows to override
appstream screenshots by local ones. The latter is e.g. used by KTrip
which provides Android-specific screenshots that way.

- Search for a suitable `tar` program
- Check version output if it's GNU tar

Since this function is typically run only once per repo,
there's not much point in doing extra cache work or writing
a separate find-module.

This should improve the alignment issues currently seen in bullet point
lists that we use frequently in the description text.

BUG: 424392

This makes use of the CMake 3.19 DEFER command to list all MODULE
targets after processing the toplevel CMakeLists. This allows us to
collect required dependencies of all plugins without changes to the
application. For example, this will fix Okular not including Poppler
because it is only linked from the plugin, thus not being able to
actually read PDFs.