feat: allow different resource configuration for idle

[Wandang]

The scenario I wanted to tackle:

When I am working on my PC I want to share a bit of my compute for the foldingathome project. But when I am idling I would like to share much more compute with the foldingathome project.

The frontend and backend would not allow this to be configured, so I added the configuration in both projects(Frontend PR).

I am normally used to nestJS and typescript for the backend, so I used AI to assist me with the task. The code looks correct to me (I did a bit of cpp over 10 years ago). I tested it locally by adding a button in the frontend that would toggle a mock idle state in the backend
The idea for this solution was adding 2 flags in the configuration that mimics the old behavior:

cpus_idle
gpus_idle

and 1 new flag that controls which resources are taken at idle time:

different_idle_resources

{
  "on_idle":                  false,
  "different_idle_resources": false,
  "on_battery":               true,
  "keep_awake":               true,
  "paused":                   true,
  "finish":                   false,
  "beta":                     false,
  "cuda":                     true,
  "hip":                      true,
  "key":                      0,
  "cpus":                     0,
  "cpus_idle":                0,
  "gpus":                     {},
  "gpus_idle":                {}
}