Implement setnx command

[codecov[bot]]

Codecov Report

Base: 80.33% // Head: 80.33% // Increases project coverage by +0.00% :tada:

Coverage data is based on head (0566330) compared to base (42dcc3e). Patch coverage: 80.65% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #210 +/- ## ======================================= Coverage 80.33% 80.33% ======================================= Files 133 134 +1 Lines 8012 8043 +31 ======================================= + Hits 6436 6461 +25 - Misses 1576 1582 +6 ``` | [Impacted Files](https://codecov.io/gh/danielealbano/cachegrand/pull/210?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano) | Coverage Δ | | |---|---|---| | [.../module/redis/command/module\_redis\_command\_setnx.c](https://codecov.io/gh/danielealbano/cachegrand/pull/210/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano#diff-c3JjL21vZHVsZS9yZWRpcy9jb21tYW5kL21vZHVsZV9yZWRpc19jb21tYW5kX3NldG54LmM=) | `80.65% <80.65%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano)

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