test: add command tests

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 62.45%. Comparing base (fbb058b) to head (4705457).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #4 +/- ## =========================================== + Coverage 34.35% 62.45% +28.10% =========================================== Files 25 25 Lines 1112 1489 +377 =========================================== + Hits 382 930 +548 + Misses 730 559 -171 ```

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[github-actions[bot]]

Bencher

Report	Mon, March 11, 2024 at 23:48:52 UTC
Project	theseus-rs/rsql
Branch	add-command-tests
Testbed	localhost

Benchmark	Latency	Latency Results nanoseconds (ns)
version	➖ (view plot)	44562000.000

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