* fixesopenziti/ziti#3626 omit overlay bind points from /versions apiBaseUrls
- adds BindPointTypeUnderlay and BindPointTypeOverlay constants
- implements Type() on UnderlayBindPoint and OverlayBindPoint
- skips non-underlay bind points when building apiBaseUrls in version_router
- skips non-underlay bind points in GetApiAddresses
- adds unit tests for Type() on both bind point implementations
- updates xweb