Implement sparse index support #1084

Job	Run time
Linting, formatting, documentation, etc	34s
testing / Run unit tests	45s
testing / Example app: semantic search	41s
testing / Setup	46s
testing / TS compile (~4.5.0)	21s
testing / external-app	2m 27s
testing / TS compile (~4.6.0)	21s
testing / TS compile (~4.7.0)	21s
testing / TS compile (~4.8.0)	24s
testing / TS compile (~4.9.0)	21s
testing / TS compile (~5.0.0)	22s
testing / TS compile (~5.1.0)	20s
testing / TS compile (~5.2.0)	24s
testing / TS compile (~5.3.0)	21s
testing / TS compile (~5.4.0)	20s
testing / TS compile (~5.5.0)	21s
testing / TS compile (~5.6.0)	20s
testing / TS compile (latest)	25s
testing / Run integration tests (prod, 18.x, npm, node)	3m 18s
testing / Run integration tests (prod, 18.x, npm, edge)	3m 24s
testing / Run integration tests (prod, 18.x, bun, node, 1.0.0)	3m 23s
testing / Run integration tests (prod, 18.x, bun, node, 1.0.36)	3m 19s
testing / Run integration tests (prod, 18.x, bun, node, 1.1.11)	3m 7s
testing / Run integration tests (prod, 20.x, npm, node)	1m 25s
testing / Run integration tests (prod, 20.x, npm, edge)	3m 30s
testing / Run integration tests (prod, 20.x, bun, node, 1.0.0)	4m 17s
testing / Run integration tests (prod, 20.x, bun, node, 1.0.36)	3m 38s
testing / Run integration tests (prod, 20.x, bun, node, 1.1.11)	3m 58s
testing / Teardown	0s
	43m 13s

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