Expose SystemState for mocking ReceiptMeta instances in tests

[hashcashier]

Can't create a ReceiptMeta without a SystemState instance.

[github-actions]

Benchmark for Linux-cuda

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Benchmark for Linux-default 7f55e9e

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Test	Base	PR	%
fib/100/execute	56.9±0.31ms	56.8±0.21ms	-0.18%
fib/100/prove	5.1±0.05s	5.1±0.03s	0.00%
fib/100/total	5.8±0.82s	5.2±0.01s	-10.34%
fib/1000/execute	79.9±0.64ms	78.9±0.65ms	-1.25%
fib/1000/prove	5.2±0.03s	5.2±0.03s	0.00%
fib/1000/total	5.4±0.05s	5.2±0.03s	-3.70%
fib/10000/execute	299.8±0.89ms	298.4±0.48ms	-0.47%
fib/10000/prove	21.3±0.22s	21.3±0.07s	0.00%
fib/10000/total	22.1±0.35s	21.6±0.07s	-2.26%

Benchmark for macOS-default 7f55e9e

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Test	Base	PR	%
fib/100/execute	29.8±0.04ms	28.9±0.04ms	-3.02%
fib/100/prove	3.7±0.07s	3.7±0.06s	0.00%
fib/100/total	3.7±0.05s	3.7±0.08s	0.00%
fib/1000/execute	40.9±0.08ms	39.5±0.11ms	-3.42%
fib/1000/prove	3.7±0.02s	3.7±0.04s	0.00%
fib/1000/total	3.7±0.07s	3.7±0.05s	0.00%
fib/10000/execute	150.3±0.30ms	141.2±0.15ms	-6.05%
fib/10000/prove	15.3±0.05s	15.2±0.10s	-0.65%
fib/10000/total	15.4±0.13s	15.3±0.06s	-0.65%

Benchmark for macOS-metal

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[SchmErik]

Looks good to me!

[github-actions]

Benchmark for Linux-cuda

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Benchmark for Linux-default

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Benchmark for macOS-default e3b3317

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Test	Base	PR	%
fib/100/execute	29.7±0.02ms	29.0±0.04ms	-2.36%
fib/100/prove	3.7±0.08s	3.7±0.09s	0.00%
fib/100/total	3.8±0.04s	3.7±0.06s	-2.63%
fib/1000/execute	40.4±0.15ms	39.3±0.15ms	-2.72%
fib/1000/prove	3.7±0.07s	3.7±0.06s	0.00%
fib/1000/total	3.8±0.04s	3.8±0.07s	0.00%
fib/10000/execute	143.8±0.19ms	139.9±0.17ms	-2.71%
fib/10000/prove	15.3±0.15s	15.3±0.10s	0.00%
fib/10000/total	15.5±0.18s	15.4±0.10s	-0.65%

Benchmark for macOS-metal

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