feat: Add desktop notifications support on Linux. #405

Job	Run time
Fedora with ASAN (full, Debug)	6m 56s
Debian (minimal, Debug)	5m 41s
Update nightly release tag	4s
Clang-Tidy	11m 4s
Docs	1m 56s
Alpine (full, Debug)	11m 44s
macOS user	12m 6s
Ubuntu LTS (full, Release)	6m 18s
Check for translatable strings	29s
Android	5m 49s
macOS distributable	5m 49s
Flatpak	12m 55s
Windows (i686, Debug)	7m 15s
Windows (i686, Release)	6m 40s
Windows (x86_64, Debug)	8m 49s
Windows (x86_64, Release)	8m 8s
	1h 51m 43s

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