Support reporting statistics in spark datasource

[robert3005]

Spark mostly focuses on sizeInBytes which we populate from file sizes with
scaling. We also report numRows since that exists in our datasource.

[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.

⚡ 2 improved benchmarks
❌ 1 regressed benchmark
✅ 1234 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	fast_lt_out_of_range[4, 65536]	204.3 µs	262.3 µs	-22.09%
⚡	Simulation	baseline_eq[16, 65536]	287.6 µs	259.6 µs	+10.78%
⚡	Simulation	baseline_lt[16, 65536]	302.7 µs	274.7 µs	+10.19%

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 rk/sparkstats (41c0d4f) with develop (012d0ec)}