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>

Polygon - Generate Geo polygon around a specific point (#53)

* Add Polygon class with geospatial methods and tests

Implemented a new static `Polygon` class in the `GeoUK` namespace for generating polygons around geographic points. The class includes input validation and methods for degree-radian conversion.

Also added a suite of unit tests in `PolygonTests.cs` using Xunit to cover various scenarios, ensuring the correctness and performance of the `GeneratePolygonAroundPoint` method.

* Fix longitude normalization in Polygon.cs

Updated longitude normalization to the range of [-180, 180]
instead of [-180, 180). Adjusted logic to correctly handle
values exceeding the bounds by adding or subtracting 360.0
as necessary, ensuring proper wrapping of longitude values.

* Add GeoUK.OSTN.XUnit project and update README.md

- Included a new project `GeoUK.OSTN.XUnit` in the solution.
- Added `pr.yml` to the Solution Items section.
- Enhanced `README.md` with a new section on generating polygons around points, including code examples and a link to GeoJson.io for testing.

Release.yml fixes (#49)

* Update project files for packaging enhancements

Added icon file for packaging and updated project metadata.
Replaced `<PackageIconUrl>` with `<PackageIcon>` for local reference.
Modified `<Description>` and restored `<Copyright>` in `GeoUK.csproj`.

* Update NuGet package paths in release.yml

Added "IeuanWalker." prefix to GeoUK and GeoUK.OSTN
packages in upload and publish paths. This ensures
correct referencing of new package names during the
release process.