feat(subscriptions): add cmd to gen json schema

This commit introduces the 'notification-schema' command to generate a
JSON schema of the Notification struct which gets sent when notifying
subscribers of updates.

komorebic.lib.sample.ahk

@@ -278,4 +278,8 @@ ToggleMouseFollowsFocus() {
 
 AhkLibrary() {
     Run, komorebic.exe ahk-library, , Hide
+}
+
+NotificationSchema() {
+    Run, komorebic.exe notification-schema, , Hide
 }