Fix redundant endpoint calls for updating selected lights

[mgibbs1259]

Is your feature request related to a problem? Please describe.
When a user changes the input lights, we make two endpoint calls. The first is to terminate the existing spotihue task and the second is to restart the spotihue task with the new lights. Instead of doing this, we should just replace the lights list with the updated one in the currently running task.

Describe the solution you'd like
Consider taking the diff between currently running task lights and new request's input lights, and using task.replace({new lights list}) in the case of the lights lists differing (ie, replacing the currently running task in 1 endpoint call instead of terminating it and then re-running it in 2 endpoint calls)

Describe alternatives you've considered
NA

Additional context
NA