LatitudeLongitude from easting northing helper (#54)

* Refactor LatitudeLongitude class and add conversion method

Updated `LatitudeLongitude.cs` to include new using directives for `GeoUK.Ellipsoids` and `GeoUK.Projections`. The class structure has been improved for clarity, and a new static method `FromEastingNorthing` has been added to convert easting and northing coordinates to latitude and longitude using Cartesian transformations and projections.

* Update GeoUK/Coordinates/LatitudeLongitude.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Fix comment typo in LatitudeLongitude.cs

Removed incorrect comment about ETRS89 and WGS84.
No changes to functionality; transformation logic remains intact.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: IeuanWalker

GeoUK/Coordinates/LatitudeLongitude.cs

@@ -1,50 +1,70 @@
+using GeoUK.Ellipsoids;
+using GeoUK.Projections;
+
 namespace GeoUK.Coordinates
 {
-	/// <summary>
-	/// This immutable class represents a set of latitude/longitude/ellipsoidal height coordinates.
-	/// </summary>
-	public class LatitudeLongitude
-
-	{
-
-		/// <summary>
-		/// Constructor.
-		/// </summary>
-		/// <param name="degreesLatitude"></param>
-		/// <param name="degreesLongitude"></param>
-		public LatitudeLongitude(double degreesLatitude, double degreesLongitude)
-		{
-			Latitude = degreesLatitude;
-			Longitude = degreesLongitude;
-			EllipsoidalHeight = 0.0;
-		}
-
-		/// <summary>
-		/// Constructor.
-		/// </summary>
-		/// <param name="degreesLatitude"></param>
-		/// <param name="degreesLongitude"></param>
-		/// <param name="ellipsoidalHeight"></param>
-		public LatitudeLongitude(double degreesLatitude, double degreesLongitude, double ellipsoidalHeight)
-		{
-			Latitude = degreesLatitude;
-			Longitude = degreesLongitude;
-			EllipsoidalHeight = ellipsoidalHeight;
-		}
-
-		/// <summary>
-		/// Returns latitude in degrees.
-		/// </summary>
-		public double Latitude { get; }
-
-		/// <summary>
-		/// Returns longitude in degrees.
-		/// </summary>
-		public double Longitude { get; }
-
-		/// <summary>
-		/// returns ellipsoidal height in meters.
-		/// </summary>
-		public double EllipsoidalHeight { get; }
-	}
+    /// <summary>
+    /// This immutable class represents a set of latitude/longitude/ellipsoidal height coordinates.
+    /// </summary>
+    public class LatitudeLongitude
+    {
+        /// <summary>
+        /// Constructor.
+        /// </summary>
+        /// <param name="degreesLatitude"></param>
+        /// <param name="degreesLongitude"></param>
+        public LatitudeLongitude(double degreesLatitude, double degreesLongitude)
+        {
+            Latitude = degreesLatitude;
+            Longitude = degreesLongitude;
+            EllipsoidalHeight = 0.0;
+        }
+
+        /// <summary>
+        /// Constructor.
+        /// </summary>
+        /// <param name="degreesLatitude"></param>
+        /// <param name="degreesLongitude"></param>
+        /// <param name="ellipsoidalHeight"></param>
+        public LatitudeLongitude(double degreesLatitude, double degreesLongitude, double ellipsoidalHeight)
+        {
+            Latitude = degreesLatitude;
+            Longitude = degreesLongitude;
+            EllipsoidalHeight = ellipsoidalHeight;
+        }
+
+        /// <summary>
+        /// Returns latitude in degrees.
+        /// </summary>
+        public double Latitude { get; }
+
+        /// <summary>
+        /// Returns longitude in degrees.
+        /// </summary>
+        public double Longitude { get; }
+
+        /// <summary>
+        /// returns ellipsoidal height in meters.
+        /// </summary>
+        public double EllipsoidalHeight { get; }
+
+        /// <summary>
+        /// Creates a <see cref="LatitudeLongitude"/> object from easting and northing coordinates.
+        /// </summary>
+        /// <param name="easting">The easting coordinate in meters.</param>
+        /// <param name="northing">The northing coordinate in meters.</param>
+        /// <returns>A <see cref="LatitudeLongitude"/> object representing the converted coordinates.</returns>
+        public static LatitudeLongitude FromEastingNorthing(double easting, double northing)
+        {
+            // Convert to Cartesian
+            Cartesian cartesian = Convert.ToCartesian(new Airy1830(),
+                    new BritishNationalGrid(),
+                    new EastingNorthing(easting, northing));
+
+            // ETRS89 is effectively WGS84
+            Cartesian wgsCartesian = Transform.Osgb36ToEtrs89(cartesian);
+
+            return Convert.ToLatitudeLongitude(new Wgs84(), wgsCartesian);
+        }
+    }
 }