Show notification when plugin host fails to start

This one's a bit generic since the relevant output from the Wine process
will have already been printed to the logger before this point.

CHANGELOG.md

@@ -10,6 +10,11 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Added
 
+- When the Wine plugin host process fails to start, yabridge will now show a
+  desktop notification to notify you about this. This lets you diagnose issues
+  faster if you didn't already start your DAW from a terminal. These
+  notifications require `libnotify` and the `notify-send` application to be
+  installed.
 - Added an environment variable to disable the watchdog timer. This allows the
   Wine process to run under a separate namespace. If you don't know that you
   need this, then you probably don't need this!

src/plugin/bridges/common.h

@@ -310,6 +310,16 @@ class PluginBridge {
                     generic_logger.log(
                         "The Wine host process has exited unexpectedly. Check "
                         "the output above for more information.");
+
+                    // Also show a desktop notification so users running from
+                    // the GUI get a heads up
+                    send_notification(
+                        "Failed to start the Wine plugin host",
+                        "Check yabridge's output for more information on what "
+                        "went wrong. You may need to rerun your DAW from a "
+                        "terminal and restart the plugin scanning process to "
+                        "see the error.");
+
                     std::terminate();
                 }