remove autofrontlight + backgroundrunner (#12809)

* remove autofrontlight
* remove background-runner

thirparty plugins that rely on the backgroundrunner no longer work.

frontend/pluginshare.lua

@@ -1,6 +1,4 @@
 -- PluginShare is a table for plugins to exchange data between each other.
 -- It is a singleton, which will persist across views (and, as such, across plugins lifecycle).
 -- Plugins should maintain their own protocols.
-return {
-    backgroundJobs = {},
-}
+return {}