Add fx-to-dotnet to community extension catalog (#2471)

* Add fx-to-dotnet to community extension catalog

- Extension ID: fx-to-dotnet
- Version: 0.8.0
- Author: RogerBestMsft
- .NET Framework to Modern .NET Migration

Closes #2469

* Address review: remove tool version, fix table ordering

- Remove meaningless >=0.0.0 version from required tool entry
- Move .NET Framework row to correct alphabetical position (after Multi-Model Review)
- Lowercase link label to match table conventions