New python service for poller, discovery + more (#8455)

Currently has a file handle leak (and will eventually run out of handles) related to the self update process.

Either need to fix that or rip out self-update and leave that up to cron or something.


DO NOT DELETE THIS TEXT

#### Please note

> Please read this information carefully. You can run `./scripts/pre-commit.php` to check your code before submitting.

- [x] Have you followed our [code guidelines?](http://docs.librenms.org/Developing/Code-Guidelines/)

#### Testers

If you would like to test this pull request then please run: `./scripts/github-apply <pr_id>`, i.e `./scripts/github-apply 5926`

LibreNMS/Config.php

@@ -314,6 +314,18 @@ class Config
         return is_array($curr) && isset($curr[$last]);
     }
 
+    /**
+     * Serialise the whole configuration to json for use in external processes.
+     *
+     * @return string
+     */
+    public static function json_encode()
+    {
+        global $config;
+
+        return json_encode($config);
+    }
+
     /**
      * merge the database config with the global config
      * Global config overrides db