gRPC - update existing services

[codymullins]

Currently, Spacetime supports adding new gRPC services using reflection. We now need support for updating these services.

Simple

• Right click on a service, the context menu should have an "update" menu item
• Clicking this menu item should refresh the service

Advanced

• Right click on a service, the context menu should have an "update" menu item with a submenu "update" and "update (advanced)" todo: choose better naming
• Clicking this menu item (advanced) should open a popup allowing a user to change the settings for the service. for now, just the host URL

Notes

• Simple method should not prompt the user again in most scenarios
• Should show a loading indicator for the service and a little checkmark when done
• Should show an error if something bad happened and let the user take an action