Retry adding controls for slow workers

[db0]

Slow worker being one that is at < 0.3 MPS/s

Ideas:

• [x] Add a switch for people to request to exclude slow workers from their generations. Provide a kudos discount when the user opts to allow slow workers.
• [ ] Only send jobs to slow workers only if n < 5 (Won't work well with artbot which splits all requests anyway though)
• [ ] If worker speed drops below 0.1 MPS/s for X generations, perhaps consider putting it in maintenance?

[db0]

Relevant to: https://github.com/sdwebui-w-horde/sd-webui-stable-horde-worker/issues/84

[arekku255]

Idea: Add a parameter for slowest worker allowed.

This way the API user is in control of what is considered a slow worker and what they are willing to accept.

Iteration: Add a parameter for soft realtime limit. This parameter describes how long the requestor is willing to wait for a reply. If the request is deemed impossible to fulfil it will be rejected. The job will only be given to a worker that can plausibly complete the request before the timer runs out.

As a user I don't really care about how long the request takes to run, I am more concerned with the total time taken, wait time + generation time.

60 seconds wait and 240 seconds to generate is the same to me as 240 seconds wait and 60 seconds to generate.

[arekku255]

The soft realtime limit could affect the kudos cost, where a higher limit results in lower costs.