逻辑删除情况下加工查询对象
@param {Object} name - 模型名称
@param {Object} query - 查询对象
@param {Object} opts - 适配器配置
function tombstoneQuery(name, query, opts) {
    const tombstoneKey = opts && (typeof opts.tombstoneKeyGetter === 'function') ? opts.tombstoneKeyGetter(name) : null;
    if (!tombstoneKey) return query;

    const cond = { [tombstoneKey]: { $ne: true } };
    if (query._conditions.$and && Array.isArray(query._conditions.$and)) {
        query._conditions.$and.push(cond);
    } else {
        Object.assign(query._conditions, cond);
    }
    return query;
}