Move to systemd-lock-handler instead of swayidle for locking

Swayidle will likely end up dropping logind support, and they themselves
describe it as unstable. For this reason, move to the suggested
alternative: systemd-lock-handler, and just have swayidle run the
command to trigger the logind session lock event, picked up by
systemd-lock-handler.

See <https://github.com/swaywm/swayidle/issues/117> for reference.

home/.config/swayidle/config

@@ -1,4 +1,2 @@
 timeout 300 "hyprctl dispatch dpms off && dunstctl set-paused true" resume "hyprctl dispatch dpms on && dunstctl set-paused false"
 timeout 310 "loginctl lock-session"
-before-sleep swaylock -fF
-lock swaylock -fF

home/.config/systemd/user/default.target.wants/systemd-lock-handler.service

@@ -0,0 +1 @@
+/usr/lib/systemd/user/systemd-lock-handler.service

home/.config/systemd/user/lock.target.wants/systemd-lock-handler-swaylock.service

@@ -0,0 +1 @@
+/home/itsdrike/.config/systemd/user/systemd-lock-handler-swaylock.service

home/.config/systemd/user/systemd-lock-handler-swaylock.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=Run Swaylock screenlocker on lock dbus event (using systemd-lock-handler)
+# if swaylock exists cleanly, unlock this session
+OnSuccess=unlock.target
+# When lock.target is stopped, stop this too
+PartOf=lock.target
+# Delay lock.target until this service is ready
+After=lock.target
+
+[Service]
+# systemd will consider this service started when swaylock forks
+# which swaylock will only do after it has locked the screen
+Type=forking
+ExecStart=/usr/bin/swaylock -fF
+Restart=on-failure
+
+[Install]
+WantedBy=lock.target