Add `export.Handler` #9154

Job	Run time
check-links	10s
compatibility-test (~1.24.0, ubuntu-latest, amd64)	1m 49s
lint (ubuntu-latest)	2m 54s
compatibility-test (~1.23.1, ubuntu-latest, amd64)	49s
lint (ubuntu-22.04-arm)	3m 22s
race-test	2m 18s
verify-licenses	41s
	12m 3s

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