Add macOS, Windows, & Ubuntu 22.04 Qt6 builds (#4522)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

.docker/Dockerfile-ubuntu-22.04-qt6-package

@@ -0,0 +1,23 @@
+ARG UBUNTU_VERSION=22.04
+
+FROM chatterino-ubuntu-$UBUNTU_VERSION-qt6-build
+
+# In CI, this is set from the aqtinstall action
+ENV Qt6_DIR=/opt/qt/6.2.4/gcc_64
+
+WORKDIR /src/build
+
+ADD .CI /src/.CI
+
+# Install dependencies necessary for AppImage packaging
+RUN apt-get update && apt-get -y install --no-install-recommends \
+        curl \
+        libxcb-shape0 \
+        libfontconfig1 \
+        file
+
+# package deb
+RUN ./../.CI/CreateUbuntuDeb.sh
+
+# package appimage
+RUN ./../.CI/CreateAppImage.sh