…ries#40616)

So i just discovered `editor::ExpandAllDiffHunks`

I have been really missing the ability to look at changes NOT in a multi
buffer so i was very pleased to finally figure out that this is already
possible in Zed.

i have seen alot of discussion/issues requesting this feature so i think
it is safe to say i'm not the only one that is not aware it exists.

i think the wording in the docs could better communicate what this
feature actually is, however, i think an even better way to show users
that this feature exists would be to just put it in front of them.

In the `GitPanel`:
- `menu::Confirm` opens the project diff
- `menu::SecondaryConfirm` opens the selected file in a new editor.

I think it would be REALLY nice if opening a file with
`SecondaryConfirm` opened the file with the diff hunks already expanded
and scrolled the editor to the first hunk.

ideally i see this being toggle-able in settings something like
`GitPanel - Open File with Diffs Expanded` or something. so the user
could turn this off if they preferred.

I tried creating a new keybinding using the new `actions::Sequence`
it was something like:
```json
{
  "context": "GitPanel && ChangesList",
  "bindings": {
    "cmd-enter" : [ "actions::Sequence", ["menu:SecondaryConfirm", "editor::ToggleFocus", "editor::ExpandAllDiffHunks", "editor::GoToHunk"]]
  }
}
```
but the action sequence does not work. i think because opening the file
is an async task.

i have a first attempt here, of just trying to get the diff hunks to
expand after opening the file.
i tried to copy and paste the logic/structure as best i could from the
confirm method in file_finder.rs:1432

it compiles, but it does not work, and i do not have enough experience
in rust or in this project to figure out anything further.

if anyone was interested in working on this with me i would enjoy
learning more and i think this would be a nice way to showcase this
tool!