keymap_ui: Limit length of keystroke input and hook up actions (#34464)

Closes #ISSUE

Changes direction on the design of the keystroke input. Due to MacOS
limitations, it was decided that the complex repeat keystroke logic
could be avoided by limiting the number of keystrokes so that accidental
repeats were less damaging to ux. This PR follows up on the design pass
in #34437 that assumed these changes would be made, hooking up actions
and greatly improving the keyboard navigability of the keystroke input.

Release Notes:

- N/A *or* Added/Fixed/Improved ...

assets/keymaps/default-linux.json

@@ -1120,5 +1120,14 @@
       "alt-ctrl-f": "keymap_editor::ToggleKeystrokeSearch",
       "alt-c": "keymap_editor::ToggleConflictFilter"
     }
+  },
+  {
+    "context": "KeystrokeInput",
+    "use_key_equivalents": true,
+    "bindings": {
+      "enter": "keystroke_input::StartRecording",
+      "escape escape escape": "keystroke_input::StopRecording",
+      "delete": "keystroke_input::ClearKeystrokes"
+    }
   }
 ]

assets/keymaps/default-macos.json

@@ -1217,5 +1217,14 @@
       "cmd-alt-f": "keymap_editor::ToggleKeystrokeSearch",
       "cmd-alt-c": "keymap_editor::ToggleConflictFilter"
     }
+  },
+  {
+    "context": "KeystrokeInput",
+    "use_key_equivalents": true,
+    "bindings": {
+      "enter": "keystroke_input::StartRecording",
+      "escape escape escape": "keystroke_input::StopRecording",
+      "delete": "keystroke_input::ClearKeystrokes"
+    }
   }
 ]