* fix(real_ip): get user real ip from headers of request
* fix(real_ip): compatible with those header with multiple IP values separated by commas
* test(real_ip): add benchmark for IPv4 and IPv6 private address check
* fix(real_ip): check empty, then remove leading and tailing comma char, finally locate first IP field
* test(real_ip): move checker logic into utils and add more unit test cases
* test(real_ip): write unit tests covering all code branches of the `util-ip` module
* refactor(real_ip): use one-line `testify.assert.Panics` to capture intended panic in test case
* chore(real_ip): add module private variable `UserRealIpHeaderCandidates`
put those headers together, make it easy to manage in one place
* doc(real_ip): write docstring for each function in the `utils-ip` module
* chore(real_ip): choose more concrete and unambiguous name for test helper function
It is to avoid polluting the module name-space with too general names.
* chore(naming): change function names according to code style
* refactor(real_ip): simplify the code indicated by 'gosimple' and `golangci`
* chore(naming): rename the `utils-ip` file to `utils_ip` to match with the rest of the file structure
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Co-authored-by: Felipe Martin <812088+fmartingr@users.noreply.github.com>
