Windscribe API and more servers filter options, fixes #197 (#282)

- Use Windscribe API to fetch servers information
- More data on servers about region, city and hostname
- Add optional server filters with `REGION`, `CITY` and `HOSTNAME` csv environment variables

internal/params/params.go

@@ -73,6 +73,8 @@ type Reader interface {
 
 	// Windscribe getters
 	GetWindscribeRegions() (countries []string, err error)
+	GetWindscribeCities() (cities []string, err error)
+	GetWindscribeHostnames() (hostnames []string, err error)
 	GetWindscribePort(protocol models.NetworkProtocol) (port uint16, err error)
 
 	// Surfshark getters