`keepOrphanedCachedAccessories` config option
### Current Situation

Currently `keepOrphanedCachedAccessories` is available on the CLI, and I'd like to enable it, but I'm running in docker with https://github.com/homebridge/docker-homebridge and can't find a way to set that flag.

It also looks like it's not possible to set this in the config file.

### Proposed Change

Also read `keepOrphanedCachedAccessories` from the config file. I think it could be loaded in from the config at

https://github.com/homebridge/homebridge/blob/12b5338bede5dad0c6fee038254db627eb4f958d/src/server.ts#L81

and merged into the bridge options at

https://github.com/homebridge/homebridge/blob/12b5338bede5dad0c6fee038254db627eb4f958d/src/server.ts#L107

?

### Additional Context

I'd like to disable it because I'm running my own plugin, and currently if I push a broken version it wipes out all the accessories, and setting them all back up again is a bit of a pain (because they all come back in the default room and are removed from scenes etc). I'm hoping if I turn this option on that would not happen?

Happy to prepare a PR if you're happy with the idea