Change GitCommand logic

[HardCodeDev777]

Commands are only about exectuing and rendering, not Core logic. I don't really like that in GitCommand.cs a lot of extra(for command) code. I'd like to move it to Core/.

[HardCodeDev777]

Also I'd like to move all logic related to repositories, like

public static List<string> GetRepositoriesNamesFromSetup()

To one Core script that will handle it.