Add a way to build a GpxBoundingBox from a list of points

[HarelM]

Some GPX file do not have bounds property filled.
In some cases filling this can help out when using the GPX object.
Below is the code I'm using in order to update the GPX bounds, I thought this library might be a good fit to it. If not, I can always have this code in my repository.

        public static GpxMainObject UpdateBounds(this GpxMainObject gpx)
        {
            if (gpx.Metadata?.Bounds != null &&
                gpx.Metadata.Bounds.MinLatitude.Value != 0 &&
                gpx.Metadata.Bounds.MaxLatitude.Value != 0 &&
                gpx.Metadata.Bounds.MinLongitude.Value != 0 &&
                gpx.Metadata.Bounds.MaxLongitude.Value != 0)
            {
                return gpx;
            }
            var points = (gpx.Routes ?? new List<GpxRoute>()).Where(r => r.Waypoints != null).SelectMany(r => r.Waypoints).ToArray();
            points = points.Concat(gpx.Waypoints ?? new List<GpxWaypoint>()).ToArray();
            points = points.Concat((gpx.Tracks ?? new List<GpxTrack>()).Where(r => r.Segments != null).SelectMany(t => t.Segments).SelectMany(s => s.Waypoints)).ToArray();
            if (!points.Any())
            {
                return gpx;
            }

            var boundingBox = new GpxBoundingBox(
                minLatitude: new GpxLatitude(points.Min(p => p.Latitude.Value)), 
                maxLatitude: new GpxLatitude(points.Max(p => p.Latitude.Value)),
                minLongitude: new GpxLongitude(points.Min(p => p.Longitude.Value)), 
                maxLongitude: new GpxLongitude(points.Max(p => p.Longitude.Value))
            );
            gpx.Metadata = gpx.Metadata == null 
                ? new GpxMetadata(null, null, null, null, null, ImmutableArray<GpxWebLink>.Empty, null, null, boundingBox, null) 
                : new GpxMetadata(gpx.Metadata.Creator, gpx.Metadata.Name, gpx.Metadata.Description, gpx.Metadata.Author, gpx.Metadata.Copyright, gpx.Metadata.Links, gpx.Metadata.CreationTime, gpx.Metadata.Keywords, boundingBox, gpx.Metadata.Extensions);
            return gpx;
        }