chore(surfshark): add package internal/provider/surshark/server

- Merge `internal/models/location.go` and `internal/constants/surfshark.go` into `internal/provider/surfshark/servers/locationdata.go`

internal/models/location.go

@@ -1,12 +0,0 @@
-package models
-
-// SurfsharkLocationData is required to keep location data on Surfshark
-// servers that are not obtained through their API.
-type SurfsharkLocationData struct {
-	Region   string
-	Country  string
-	City     string
-	RetroLoc string // TODO remove in v4
-	Hostname string
-	MultiHop bool
-}