src/vs/platform/userDataSync/common/keybindingsMerge.ts/byKeybinding
function byKeybinding(keybindings: IUserFriendlyKeybinding[], keys: IStringDictionary<string>) {
	const map: Map<string, IUserFriendlyKeybinding[]> = new Map<string, IUserFriendlyKeybinding[]>();
	for (const keybinding of keybindings) {
		const key = keys[keybinding.key];
		let value = map.get(key);
		if (!value) {
			value = [];
			map.set(key, value);
		}
		value.push(keybinding);

	}
	return map;
}