Convert keymap context to use generics and Cow<'static> so we don't have to add .to_string() and .into() for each usage

assets/keymaps/default.json

@@ -456,7 +456,7 @@
         }
     },
     {
-        "context": "Dock",
+        "context": "Dock > Pane",
         "bindings": {
             "shift-escape": "dock::HideDock",
             "cmd-escape": "dock::RemoveTabFromDock"
@@ -475,17 +475,6 @@
             "backspace": "project_panel::Delete"
         }
     },
-    {
-        "context": "ProjectPanel > Editor",
-        "bindings": {
-            "left": "editor::MoveLeft",
-            "right": "editor::MoveRight",
-            "backspace": "editor::Backspace",
-            "cmd-x": "editor::Cut",
-            "cmd-c": "editor::Copy",
-            "cmd-v": "editor::Paste"
-        }
-    },
     {
         "context": "Terminal",
         "bindings": {