Geo: Add Workhorse function to call `/api/v4/internal/geo_proxy`

To do

• Determine where in the Workhorse code we should make the request to /api/v4/internal/geo_proxy
  • I chose a location immediately before we look for a matching route. The main thing is that this check cannot occur only on startup of Workhorse, because e.g. a Geo secondary can be promoted to be the primary. So the check location must be in the request flow. This is also why it must be cached.
• Add a function to make the request
• Just output the result of the request as debug logs for now
• Call the function if environment variable GEO_SECONDARY_PROXY=1
• Tests

Where does this fit in the epic?

Description	Issue
Add endpoint /api/v4/geo/proxy	#324664 (closed)	!63343 (merged)
Determine if this is a Geo Proxy by calling /api/v4/geo/proxy	#329670 (closed) You are here	!60769 (merged)
If this is a Geo Proxy, then use the Geo Proxy routing table	#329672 (closed)	!63321 (merged)
Before we can remove the environment variable, we must add caching of the result of the request	#329671 (closed)