When using RESP3, ZPOPMAX/ZPOPMIN should return nested arrays for consistency
with other commands (e.g. ZRANGE).
We do that only when COUNT argument is present (similarly to how LPOP behaves).
for reasoning see https://github.com/redis/redis/issues/8824#issuecomment-855427955
This is a breaking change only when RESP3 is used, and COUNT argument is present!
(cherry picked from commit 7f342020dcbdf9abe754d6b666efdeded7063870)
f497eb3cca