Improve SLT test harness

[AdamGS]

Summary

This PR improves the SLT test harness in the following way

1. Uses libtest-mimic that the underlying sqllogictest crate re-exports to get support for nextest and better filtering!
2. Adds a --complete flag that can just fill-in results
3. Replaces $__TEST_DIR__ with ${WORK_DIR} that is a test-only scratch dir that gets cleaned up at the end of the test.
4. Also improved the README and other docs

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 4 improved benchmarks
❌ 2 regressed benchmarks
✅ 1583 untouched benchmarks
⏩ 4 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	chunked_varbinview_into_canonical[(1000, 10)]	168.8 µs	205.6 µs	-17.87%
❌	Simulation	slice_empty_vortex	310 ns	368.3 ns	-15.84%
⚡	Simulation	chunked_varbinview_opt_canonical_into[(1000, 10)]	205.9 µs	169.4 µs	+21.54%
⚡	Simulation	bitwise_not_vortex_buffer_mut[128]	244.4 ns	215.3 ns	+13.55%
⚡	Simulation	bitwise_not_vortex_buffer_mut[1024]	304.7 ns	275.6 ns	+10.58%
⚡	Simulation	eq_i64_constant	318.6 µs	288.7 µs	+10.35%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing adamg/improve-slt (0cc13dd) with develop (b0fb9f1)}

Footnotes

1. 4 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩