fix: Eagerly compute property value count indexes

[RobertJacobsonCDC]

Fixes a correctness bug and adds regression tests for an issue with value count indexes. Apparently we failed to initialize the index upon creation. Consequently, it's possible for a value count index to incorrectly count the number of entities with particular values.

The fix is simple: just compute the index when it is created.

[github-actions]

Benchmark Results

Hyperfine

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
large_sir::baseline	2.7 ± 0.0	2.6	2.9	1.00
large_sir::baseline_households	2.7 ± 0.0	2.6	2.9	1.00 ± 0.03
large_sir::entities	6.2 ± 0.1	6.0	6.4	2.29 ± 0.05
large_sir::households	6.0 ± 0.1	5.8	6.4	2.22 ± 0.05

Criterion

Regressions (slower)

Group	Bench	Param	Change	CI Lower	CI Upper
sampling	sampling_multiple_known_length_entities		11.447%	10.058%	12.902%
large_dataset	bench_query_population_indexed_property_entities		3.207%	1.767%	4.725%
indexing	with_query_results_indexed_multi-property_entities		2.314%	1.705%	3.046%
sampling	sampling_single_l_reservoir_entities		2.229%	2.138%	2.312%
counts	multi_property_indexed_entities		1.571%	1.134%	2.120%

Improvements (faster)

Group	Bench	Param	Change	CI Lower	CI Upper
sample_entity	sample_entity_multi_property_indexed	100000	-22.188%	-22.919%	-21.427%
sample_entity	sample_entity_multi_property_indexed	1000	-20.769%	-21.873%	-19.674%
sample_entity	sample_entity_multi_property_indexed	10000	-19.995%	-21.032%	-18.914%
sample_entity	sample_entity_single_property_indexed	1000	-13.519%	-15.718%	-10.967%
sample_entity	sample_entity_whole_population	10000	-9.594%	-12.161%	-6.869%
sampling	sampling_multiple_l_reservoir_entities		-8.583%	-8.933%	-8.168%
sample_entity	sample_entity_single_property_indexed	100000	-8.040%	-9.476%	-6.701%
indexing	query_people_multiple_individually_indexed_properties_entities		-4.742%	-4.905%	-4.584%
sample_entity	sample_entity_whole_population	100000	-4.615%	-6.947%	-2.247%
sampling	sampling_multiple_unindexed_entities		-3.974%	-5.603%	-2.399%
sampling	count_and_sampling_single_unindexed_concrete_plus_derived_entiti		-3.476%	-4.702%	-2.297%
large_dataset	bench_query_population_derived_property_entities		-3.372%	-4.161%	-2.626%
sample_entity	sample_entity_single_property_unindexed	10000	-3.356%	-3.801%	-2.818%
indexing	query_people_count_multiple_individually_indexed_properties_enti		-2.076%	-2.234%	-1.909%
indexing	query_people_count_indexed_multi-property_entities		-1.836%	-2.328%	-1.341%
examples	example-births-deaths		-1.618%	-2.228%	-1.071%

Unchanged / inconclusive (CI crosses 0%)

Group	Bench	Param	Change	CI Lower	CI Upper
sample_entity	sample_entity_whole_population	1000	-2.172%	-4.841%	0.040%
sample_entity	sample_entity_single_property_indexed	10000	-2.140%	-4.684%	0.172%
sampling	sampling_single_known_length_entities		1.944%	0.582%	3.547%
sampling	count_and_sampling_single_known_length_entities		-1.456%	-3.803%	1.099%
examples	example-basic-infection		-1.445%	-2.193%	-0.729%
large_dataset	bench_query_population_multi_indexed_entities		-1.197%	-1.720%	-0.729%
sampling	sampling_single_unindexed_entities		-1.053%	-2.781%	0.763%
large_dataset	bench_query_population_multi_unindexed_entities		0.666%	0.250%	0.965%
counts	index_after_adding_entities		0.628%	0.414%	0.845%
indexing	query_people_indexed_multi-property_entities		0.578%	0.192%	1.015%
counts	single_property_unindexed_entities		0.573%	-0.451%	1.795%
algorithm_benches	algorithm_sampling_multiple_l_reservoir		-0.557%	-0.964%	-0.164%
large_dataset	bench_filter_unindexed_entity		-0.540%	-4.163%	3.269%
counts	single_property_indexed_entities		0.453%	-0.030%	0.979%
sample_entity	sample_entity_single_property_unindexed	1000	-0.445%	-0.822%	-0.070%
sample_entity	sample_entity_single_property_unindexed	100000	0.372%	-1.587%	2.262%
counts	concrete_plus_derived_unindexed_entities		-0.349%	-0.846%	-0.009%
indexing	with_query_results_single_indexed_property_entities		-0.336%	-1.000%	0.458%
large_dataset	bench_match_entity		0.300%	-1.439%	2.017%
sampling	sampling_single_unindexed_concrete_plus_derived_entities		0.278%	-1.133%	1.665%
algorithm_benches	algorithm_sampling_single_l_reservoir		0.270%	-0.315%	1.110%
algorithm_benches	algorithm_sampling_single_known_length		-0.258%	-1.798%	1.270%
indexing	query_people_count_single_indexed_property_entities		0.236%	-0.182%	0.615%
indexing	query_people_single_indexed_property_entities		-0.172%	-0.272%	-0.090%
large_dataset	bench_query_population_property_entities		-0.156%	-0.807%	0.318%
algorithm_benches	algorithm_sampling_multiple_known_length		0.127%	-0.214%	0.472%
large_dataset	bench_filter_indexed_entity		0.063%	-1.830%	1.927%
algorithm_benches	algorithm_sampling_single_rand_reservoir		-0.058%	-0.551%	0.472%
counts	reindex_after_adding_more_entities		0.049%	-0.090%	0.179%
counts	multi_property_unindexed_entities		-0.043%	-0.662%	0.518%
indexing	with_query_results_multiple_individually_indexed_properties_enti		-0.021%	-0.636%	0.649%

Not Compared (no baseline yet)

Group	Bench	Reason
(none)