Add `map` for `ServiceConfig` #2756

Job	Run time
test (examples)	7m 10s
typos	3s
test (utoipa)	5s
test (utoipa-gen)	7s
test (utoipa-swagger-ui-vendored)	10s
test (utoipa-swagger-ui)	5s
test (utoipa-redoc)	10s
test (utoipa-rapidoc)	9s
test (utoipa-scalar)	10s
test (utoipa-axum)	7s
test (utoipa-config)	11s
test (utoipa-actix-web)	1m 2s
	9m 29s

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