feat(SchemaStore): add `getIdentifier` method #3749

Job	Run time
Linting	1m 8s
Docgen / Run yarn job	3m 4s
Tests / Unit testing	4m 21s
Check Dynamic Side Effects / Run yarn job	58s
Check Package Index Files / Run yarn job	50s
Check subpaths / Run yarn job	31s
Building / Building / Run yarn job	2m 24s
	13m 16s

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