Add missing options to the hypervisor

[Senyoret1]

Feature description
The manager UI has some options in the testnet that can not be implemented in the mainnet with the current hypervisor API. The options are:

Those options are for setting the address of the discovery service, checking updates for the node/visor and restarting the node/visor. Also, the mainnet UI currently has an option for selecting if the visor should act as an exit node, but there is no API endpoint for making it work.

Is your feature request related to a problem? Please describe.
There are some options in the manager that are not working and can not be implemented with the curren API.

Describe the solution you'd like
API endpoints must be added to make those options work, or the options should be removed from the UI.

Describe alternatives you've considered

Additional context

Possible implementation

[jdknives]

@Senyoret1 We probably do not need to support the discovery option, since I believe it is meant to allow the user to switch the discovery used. I cannot see a use for it right now. The reboot endpoint needs to be implemented I believe and the Update endpoint needs to be discussed with Synth.

[jdknives]

Related to #64

[jdknives]

Am closing this, as the updating endpoint will be implemented by #153