Fetch "activity types" data for speed data for activities

[mcescalante]

There were discussions of getting walking speed data into OH and after looking at the Fitbit API it looks like there are 2 different API endpoints that aren't being utilized that contain activity speed information:

1. "Activities list" which contains a single speed datapoint for an entire activity
2. "Activity type" which returns more detailed information about an activity including min & max speed per "level" https://dev.fitbit.com/build/reference/web-api/activity/#get-activity-type

We should add in the latter to our fetching to see how much data accumulates for someone who has years worth of activity data.