feat: add redis and redis-cluster in limit-req

[theweakgod]

Description

Fixes https://github.com/apache/apisix/issues/10501 (https://github.com/apache/apisix/issues/10501) Add options for redis and redis-cluster in the limit-req plugin, and use redis as the counter.

Checklist

• [x] I have explained the need for this PR and the problem it solves
• [x] I have explained the changes or the new features added to this PR
• [x] I have added tests corresponding to this change
• [x] I have updated the documentation to reflect this change
• [ ] I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[shreemaan-abhishek]

I would suggest working on this only after redis support for limit-conn is merged.

[theweakgod]

I would suggest working on this only after redis support for limit-conn is merged.

Yeah, I think so.

[shreemaan-abhishek]

@theweakgod we may start working on this now. Please make changes carefully and diligently considering the code review we did for limit-conn. Your cooperation is highly appreciated <3

[theweakgod]

@theweakgod we may start working on this now. Please make changes carefully and diligently considering the code review we did for limit-conn. Your cooperation is highly appreciated <3

ok

[theweakgod]

@shreemaan-abhishek @monkeyDluffy6017 I'm ready for the review.