fix: check if `config` contains duplicate resources in API-driven standalone mode

[LiteSun]

Description

add duplicate resource check in API-driven standalone mode

Which issue(s) this PR fixes:

Fixes #12259

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
• [ ] I have updated the documentation to reflect this change
• [x] I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)