xgroup_create need a key word param such as 'create_if_not_exit'

[hsz1273327]

Checklist

• Python 3.8
• Using hiredis
• Using asyncio event loop
• Does issue exists against the master branch of aredis?

Steps to reproduce

await redis.xgroup_create(resultQ, "testconsumer", '$')

Expected behavior

create a stream and add group "testconsumer" to it.

Actual behavior

got exception

aredis.exceptions.ResponseError: The XGROUP subcommand requires the key to exist. Note that for CREATE you may want to use the MKSTREAM option to create an empty stream automatically.

the api of xgroup_create need a key word param such as 'create_if_not_exit'

• It is appreciated if error log can be provided

[nelreina]

In py_redis you have mkstream = True/False as in redis api .