[Enhancement] Custom media lifecycle scripts (#219)

* Namespaced notification modules under lifecycle

* Added a JSON encoder for all the main model types

* Added startup task to create user script file

* Hook up user script event to media download

* Hooked up media deletion user script

* Added jq to docker deps

* Updated README

config/config.exs

@@ -14,7 +14,7 @@ config :pinchflat,
   yt_dlp_executable: System.find_executable("yt-dlp"),
   apprise_executable: System.find_executable("apprise"),
   yt_dlp_runner: Pinchflat.YtDlp.CommandRunner,
-  apprise_runner: Pinchflat.Notifications.CommandRunner,
+  apprise_runner: Pinchflat.Lifecycle.Notifications.CommandRunner,
   media_directory: "/downloads",
   # The user may or may not store metadata for their needs, but the app will always store its copy
   metadata_directory: "/config/metadata",