src/vs/platform/userDataSync/common/keybindingsMerge.ts/byCommand
function byCommand(keybindings: IUserFriendlyKeybinding[]): Map<string, IUserFriendlyKeybinding[]> {
	const map: Map<string, IUserFriendlyKeybinding[]> = new Map<string, IUserFriendlyKeybinding[]>();
	for (const keybinding of keybindings) {
		const command = keybinding.command[0] === '-' ? keybinding.command.substring(1) : keybinding.command;
		let value = map.get(command);
		if (!value) {
			value = [];
			map.set(command, value);
		}
		value.push(keybinding);
	}
	return map;
}