Modified git fetch command to method to use correct root folder.

[janbro]

Motivation

#6108
Forge init --template fails when passing a directory that's different than the CWD since a git command is not ran in the correct context.

Solution

Change Git::fetch to a method and use the context from the instantiate Git object

[mattsse]

thanks, test looks fine,

pending @Evalir

[Evalir]

thanks! looks good