[feat] Allow tracking of a standalone project w/o workspace

[vhespanha]

Hey there,

I've got a bit of a unique use case. I don't want Projections to track all git repos in my home folder, but I do need it to track one specific repo (my dotfiles repo located at ~/dotfiles).

I couldn't find a way to specify a standalone project like that—only to specify workspaces. I know there are workarounds, but I think implementing this feature would give the plugin more flexibility.

It would be great to have syntax to expose only one project from a directory without a parent workspace tracking it.

I'll probably submit a PR this weekend to take a swing at implementing this.