Add `export.Handler` #9182

Job	Run time
check-links	11s
compatibility-test (~1.24.0, ubuntu-latest, amd64)	1m 51s
compatibility-test (~1.23.1, ubuntu-latest, amd64)	58s
lint (ubuntu-latest)	2m 41s
race-test	2m 3s
lint (ubuntu-22.04-arm)	3m 49s
verify-licenses	43s
	12m 16s

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