This PR adds support for the systemd notify protocol. Several status
messagess are provided. We should likely add a common notify/status
message for graceful.
Replaces #21140
Signed-off-by: Andrew Thornton <art27@cantab.net>
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Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: ltdk <usr@ltdk.xyz>
Co-authored-by: Giteabot <teabot@gitea.io>