The global counter approach is easy to understand but it's brittle and depends on implicit behaviour that is not very discoverable.
With a global counter, if any goroutine accidentally decrements the counter twice, we'll think lazygit is idle when it's actually busy.
Likewise if a goroutine accidentally increments the counter twice we'll think lazygit is busy when it's actually idle.
With the new approach we have a map of tasks where each task can either be busy or not. We create a new task and add it to the map
when we spawn a worker goroutine (among other things) and we remove it once the task is done.
The task can also be paused and continued for situations where we switch back and forth between running a program and asking for user
input.
In order for this to work with `git push` (and other commands that require credentials) we need to obtain the task from gocui when
we create the worker goroutine, and then pass it along to the commands package to pause/continue the task as required. This is
MUCH more discoverable than the old approach which just decremented and incremented the global counter from within the commands package,
but it's at the cost of expanding some function signatures (arguably a good thing).
Likewise, whenever you want to call WithWaitingStatus or WithLoaderPanel the callback will now have access to the task for pausing/
continuing. We only need to actually make use of this functionality in a couple of places so it's a high price to pay, but I don't
know if I want to introduce a WithWaitingStatusTask and WithLoaderPanelTask function (open to suggestions).
We use CommitFilesController also for the files of commits that we show
elsewhere, e.g. for branch commits, tags, or stashes. It doesn't make sense to
discard changes from those (for stashes it might be possible to implement it
somehow, but that would be a new feature), so we disallow it unless we are in
the local commits panel.
Discarding changes to an entire directory doesn't quite work correctly in all
cases; for example, if the current commit added files to the directory (but the
directory existed before) then those files won't be removed.
It might be possible to fix the command so that these cases always work for
directories, but I don't think it's worth the effort (you can always use a
custom patch for that), so let's display an error for now.
We have not been good at consistent casing so far. Now we use 'Sentence case' everywhere. EVERYWHERE.
Also Removing 'Lc' prefix from i18n field names: the 'Lc' stood for lowercase but now that everything
is in 'Sentence case' there's no need for the distinction.
I've got a couple lower case things I've kept: namely, things that show up in parentheses.
