add reading of freedesktop notifications (#125)

this monitors the session bus for calls to the notify method of the org.freedesktop.notifications interface, with the path of /org/freedesktop/notifications, and collects the parameters we are interested in, then speaks them

known limitations

* application name is not spoken because most apps send a blank string for that argument

suspected limitations

* this may or may not work on gnome, as they use a different interface for reporting notifications directly to gnome-shell, if it's detected to be running. Gnome apps on other desktops might work though. For later reference, the interface in question is org.gtk.notifications, and the path is /org/gtk/notifications
* depending on the portal backend, this may not work at all if portals are involved. For future reference, we might have to monitor the portal calls, if we end up failing to hook into the system with the current freedesktop notifications implementation introduced by this commit

.github/workflows/ci.yml

@@ -166,7 +166,12 @@ jobs:
         if: hashFiles('Cargo.lock') == ''
         run: cargo generate-lockfile
       - name: Install Dependencies
-        run: sudo apt -y install at-spi2-core systemd
+        run: sudo apt -y install at-spi2-core systemd dunst xvfb
+      - name: setup dbus and notification daemon
+        run:
+          sudo systemctl start dbus;
+          systemctl --user start dbus;
+          xvfb-run dunst --screen 0 600x400x8 &
       - name: cargo llvm-cov
         run: cargo llvm-cov --locked --lcov --output-path lcov.info
       - name: Upload to codecov.io

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "rust-analyzer.linkedProjects": [
+        "./odilia-notify/Cargo.toml"
+    ]
+}