Self-host: Allow configuration of Edge Function runtime limits

[mavcook]

It would be awesome if the CPU limits for edge functions were configurable for self-hosting. I can see why this makes sense to nt allow for the Saas, but not for the self-hosting. Since the limits are different between plans, maybe it is already configurable, but I didn't see any options in the functions docker service definition.

Reasoning / use case: I have a basic edge function that needs to do a few queries on the db and so it takes longer than 200ms to run and gets terminated.

So ideally this could be configured per edge function, but since that may be complex, my current use case is fine with a global config, as I probably only need another 100-200ms. I believe this is the relevant code. I am happy to try and contribute if this is an acceptable proposal.

[erictmnz]

agree this should be set as part of a docker variable