Add Tms property to TileLayer

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The leaflet API offers a tms option to support reverse Y-axis tile numbering for TMS services.

Although correctly implemented TMS services are supported by negating the {-y} in the templateUrl, this convenience property exposes Leaflet's TileLayer option to support it.

Usage:

var tileLayer = new TileLayer
{
    UrlTemplate = "< TMS tile provider URL >",
    Tms = true,
};