function getGrants(acl) {
    return {
        FULL_CONTROL: acl.FULL_CONTROL,
        WRITE: acl.WRITE,
        WRITE_ACP: acl.WRITE_ACP,
        READ: acl.READ,
        READ_ACP: acl.READ_ACP,
    };
}
getGrants - Get all acl grants as an object
@param {object} acl - acl from metadata
@returns {object} grants