Change keymap precedence to favor user (#37557)

Closes #35623 

Previously if a base keymap had a `null` set to an action, leading to a
`NoAction` being assigned to the keymap, if a user wanted to take
advantage of that keymap (in this particular case, `cmd-2`), the keymap
binding check would favor the `NoAction` over the user, since
technically the context depth matched better. Instead, we should always
prefer the user's settings over whatever base or default.

Release Notes:

- Fixed keymap precedence by favoring user settings over base keymap /
configs.

crates/vim/src/test/vim_test_context.rs

@@ -70,11 +70,14 @@ impl VimTestContext {
         SettingsStore::update_global(cx, |store, cx| {
             store.update_user_settings::<VimModeSetting>(cx, |s| s.vim_mode = Some(enabled));
         });
-        let default_key_bindings = settings::KeymapFile::load_asset_allow_partial_failure(
+        let mut default_key_bindings = settings::KeymapFile::load_asset_allow_partial_failure(
             "keymaps/default-macos.json",
             cx,
         )
         .unwrap();
+        for key_binding in &mut default_key_bindings {
+            key_binding.set_meta(settings::KeybindSource::Default.meta());
+        }
         cx.bind_keys(default_key_bindings);
         if enabled {
             let vim_key_bindings = settings::KeymapFile::load_asset(