Add perpetual deep_searcher scheduler

[latekvo]

No description provided.

[latekvo]

Important before merging:

• remove deep_searcher from the workers list - create a dedicated schedulers -s flag for it and webui
• add simple tasks to summarizer
• move all workload only to the workers while lifting it out of the schedulers class (deep_searcher)

It's all important, without these changes:

• each new scheduler has to have a useless llm config created for it
• schedulers are indistinguishable from core chain workers
• schedulers have to be added to the -w possible options

[latekvo]

As of 55229b7 everything works as intended, but the criteria I pointed out earlier are still not met.