add better git indicator to prompt

[LuanVSO]

the current git integration only prints the branch name, getting the status of the files will make it better
something like what the posh-git module does but without actually using anything from that module because it adds too much profile load time.
I've taken a look at their solution and it has too much dependencies on the module itself and their code is all over the place with a ton of global variables and round-abouts