Prevent add of top-level isfs folders

[isc-tleavitt]

On the latest released version, this just adds ".pkg" to sc-list.txt. We just need to prevent "Add" on this item in OnMenuItem filtering in SourceControl.Git.Extension/Utils

From @mdavidovichHst

[isc-tleavitt]

No longer relevant - we don't have sc-list.txt any more (thankfully) and the behavior here is to add everything in the ISFS folder view, which is actually right.