Qt5 source AppImages: CI

[JulianGro]

Known issues:

• Fcitx support isn't shipped in those Qt5 source AppImages, since the Qt Fcitx plugin comes from Fcitx and not Qt itself. (I wouldn't be against making a release without Fcitx support and just putting this into the changelog as “known issue” and telling people to skip this version if they want to use Fcitx.)
• Qt WebEngine cannot find Conan PulseAudio:

[12021/34460] CXX obj/media/audio/libpulse_stubs/pulse_stubs.o
FAILED: [code=1] obj/media/audio/libpulse_stubs/pulse_stubs.o 
/usr/bin/g++ -MMD -MF obj/media/audio/libpulse_stubs/pulse_stubs.o.d -DUSE_UDEV -DUSE_AURA=1 -DUSE_NSS_CERTS=1 -DUSE_OZONE=1 -DOFFICIAL_BUILD -DTOOLKIT_QT -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -DNO_UNWIND_TABLES -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -Igen/media/audio -Igen -I../../../../../qt5/qtwebengine/src/3rdparty/chromium -I../../../../../qt5/qtwebengine/src/3rdparty/chromium/third_party/perfetto/include -Igen/third_party/perfetto/build_config -Igen/third_party/perfetto -I../../../../../qt5/qtwebengine/src/3rdparty/chromium/third_party/abseil-cpp -I../../../../../qt5/qtwebengine/src/3rdparty/chromium/third_party/boringssl/src/include -I../../../../../qt5/qtwebengine/src/3rdparty/chromium/third_party/protobuf/src -Igen/protoc_out -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -fno-unwind-tables -fno-asynchronous-unwind-tables -fPIC -pipe -pthread -m64 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -Wno-unused-local-typedefs -Wno-maybe-uninitialized -Wno-deprecated-declarations -fno-delete-null-pointer-checks -Wno-comments -Wno-packed-not-aligned -Wno-dangling-else -Wno-missing-field-initializers -Wno-unused-parameter -O2 -fno-ident -fdata-sections -ffunction-sections -fno-omit-frame-pointer -g0 -fvisibility=hidden -std=gnu++14 -Wno-narrowing -Wno-class-memaccess -Wno-attributes -Wno-class-memaccess -Wno-subobject-linkage -Wno-invalid-offsetof -Wno-return-type -Wno-deprecated-copy -fno-exceptions -fno-rtti -fvisibility-inlines-hidden -c gen/media/audio/pulse/pulse_stubs.cc -o obj/media/audio/libpulse_stubs/pulse_stubs.o
gen/media/audio/pulse/pulse_stubs.cc:18:10: fatal error: pulse/pulseaudio.h: Datei oder Verzeichnis nicht gefunden
   18 | #include <pulse/pulseaudio.h>
      |          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.

A patch like this might fix it:
https://github.com/conan-io/conan-center-index/blob/master/recipes/qt/5.x.x/patches/0001-Find-fontconfig-using-pkg-config.patch
As a workaround we install libpulse-dev.

• Same with libasound2-dev and alsa/asoundlib.h