fix: kernel: do not reboot persisted processes if their OnExit behavior is None

[dr-frmr]

Problem

Kernel currently restarts all persisted processes, which is confusing for developers given that a process exits when the node is shut down. This is a draft at reworking process exit behavior to be clearer and simpler

Solution

1. On boot, only restart processes with OnExit::Restart or OnExit::Requests (TODO maybe only Restart?)
2. Preserve a process' selected OnExit behavior by fixing bug

Docs Update

I'll just have to rework this whole section of docs when we get a good solution here