Supporting the glob-style config file name

[MasahikoSawada]

The config file name with glob-style is like '/opt/redis.conf.d/*.conf'.

As per disucussion redis-dev ML( title is 'To load config file of whole directory'), supporting of glob-style config name would be effective rather than loading file of whole directory.

[oranagra]

it isn't really the same thing, but maybe #8980 solves that problem in some way?

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}