Execute LLD rules when new host is added

LLD schedules could be smarter enough to run whenever a new host is added.

The server/proxy should detect any new hosts and if they have any LLD rules, run them.

This way we don't need to be aggressive on intervals, therefore releasing unwanted pressure on Zabbix components (server/proxy/db).

It would be optimal to have this behavior when new rules are added to old hosts as well.