Redis [NEW] update XREADGROUP to support reading ALL records (pending and new) from point of last ack

request

my request is to create a single XREADGROUP command that can read ALL records (both pending and new) that have not been acknowledged.

background

currently, when using XREADGROUP, you have to choose between reading pending records and reading new records. if your consumer wants to process everything that has not been acknowledged (pending and new), it has to run two separate commands.