* add a new context menu to push local LFS object to selected remote
* supports to choose remote for fetch/pull/push/lock/unlock actions
* auto select remote if there's only one remote
* remove dotnet-tool.json because the project does not rely on any dotnet tools.
* remove Directory.Build.props because the solution has only one project.
* move src/SourceGit to src. It's not needed to put all sources into a subfolder of src since there's only one project.