Consider replacing `std::function` with lambdas for registering callbacks in OperationManager

[stiber]

This might enable passing functions that can take arbitrary numbers and types of arguments, without the need for proliferating polymorphic invocation methods in OperationManager.

Is there an issue for this? I wonder if this is something that can be solved by passing a lambda, rather than a std::function.

Originally posted by @stiber in #880