Move implementations of kernel configuration tools to capsules

[bradjc]

As discussed on a recent core call, it might be a good idea to move implementations of kernel-level configuration traits into capsules. These are mechanisms that boards can choose to use, and implement traits defined in the kernel crate, but do not (and should not) use any internal kernel interfaces, and therefore can be implemented anywhere. The implementations are intended to be conveniences for boards which might want to use them, but can also be implemented by boards directly.

Proposal

We create a new capsules crate called policies, and move the in-kernel implementations to it.

List to move

• process_policies.rs implementations
• process_checker/ implementations

Discussion

This could be a new module in the capsules/core crate. However, it might be better to entirely separate these capsules, as they are used in a very different way (to configure the kernel itself and not to provide features for userspace/application logic).