Add proof that map is injective #966

Job	Run time
docker-master	1h 31m 3s
publish-standalone-dry-run	17s
test-standalone (master, dev, default)	1m 30s
validate-docker-master	3m 36s
build-wasm-of-ocaml (master, 4.14.1)	18m 33s
standalone-haskell (master)	49m 17s
generated-files (master)	22m 33s
build-js-of-ocaml (master, 4.11.1)	5m 49s
test-amd64	2h 19m 3s
deploy-js-wasm-of-ocaml	1m 30s
docker-check-all	3s
	5h 33m 14s

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