refactor(front-matter): remove `Extractor` type #14186

Job	Run time
test-node (latest, ubuntu-latest)	13s
lint (ubuntu-latest)	33s
test (canary, ubuntu-latest)	1m 36s
lint (windows-latest)	53s
test (canary, windows-latest)	2m 5s
publish-dry-run	14s
wasm (crypto/_wasm)	3s
test (canary, macOS-latest)	1m 28s
	7m 5s

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