Add marker/icon to branches without an upstream

**Is your feature request related to a problem? Please describe.**
I juggle a lot of branches at a time. One thing that is important to me is to be able to tell easily what state a branch is in. Namely is it:
- untracked (local only, no corresponding remote branch)
- synced with remote (has remote branch that it has not diverged from in either direction)
- ahead/behind remote
- merged (in sync with the main branch in a way that the lazygit delete flow doesn't prompt with "not fully merged")

With lazygit 0.44.1 I can (fairly) easily tell if a branch is ahead/behind (yellow down/up arrows), I can really easily tell if is merged (big red "upstream gone", but could be worded better for my specific use case), and I can kinda tell that it is synced (green check, but it's a little small and hard to see in my terminal theme), but the only way to tell that a branch is untracked is to look for the _lack_ of any of the aforementioned suffixes. And that, especially combined with having `showDivergenceFromBaseBranch` turned on, makes it really hard for to scan and see which branches I have yet to push to remote.

**Describe the solution you'd like**
I would like some clear easily scannable modification to the branch line so I can quickly tell which branches I have yet to push. Whether this is a color, a prefix, a suffix, words, an icon, I don't care. Just as long as it is obvious at a glance. Ideally this would be on by default, but I'm also happy for it to be behind a config setting if other people don't want to see it.

**Describe alternatives you've considered**
I don't really have any alternate ideas other than dealing with it like I have been so far.

**Additional context**
N/A