acp: Add keybindings for authorizing tool calls (#37876)

TODO:
- [x] Double-check if we like the naming of the new actions
- [x] Only show keybinding hint once per option (e.g. if there are two
`allow_once` buttons only show it on the first one)
- [x] If there are multiple tool calls that need authorisation, only
show keybindings on the first tool call
- [x] Figure out which keybindings to use
- [x] Add linux keybindings
- [x] Add windows keybindings
- [x] Bug: long keybindings can make the buttons overflow


Release Notes:

- Add keybindings for authorizing tool calls (`agent: Allow once`,
`agent: Allow always`, `agent: Reject once`) in the agent panel

---------

Co-authored-by: Agus Zubiaga <agus@zed.dev>

assets/keymaps/default-linux.json

@@ -247,7 +247,10 @@
       "ctrl-shift-e": "project_panel::ToggleFocus",
       "ctrl-shift-enter": "agent::ContinueThread",
       "super-ctrl-b": "agent::ToggleBurnMode",
-      "alt-enter": "agent::ContinueWithBurnMode"
+      "alt-enter": "agent::ContinueWithBurnMode",
+      "ctrl-y": "agent::AllowOnce",
+      "ctrl-alt-y": "agent::AllowAlways",
+      "ctrl-d": "agent::RejectOnce"
     }
   },
   {