Fx构造函数
# new TileInfo()
通过比例尺或者分辨率来计算是否是对应的瓦片错级
Example
let tileinfo = new TileInfo();
let zoomOffset = await tileinfo.getZoomOffset(
IgsServiceEnum.WMTS, // IgsServiceEnum.IGSRestTile PortalServiceEnum.WMTS PortalServiceEnum.IGSTile
"localhost",
"6163",
"epsg_standard"
);