Prove Yoneda-like result for paths, and required lemmas #2993

Job	Run time
opam-build (supported, ubuntu-latest)	5m 1s
quick-build (supported, ubuntu-latest)	3m 12s
opam-build (latest, ubuntu-latest)	4m 40s
nix	2m 9s
opam-build (dev, ubuntu-latest)	4m 46s
quick-build (latest, ubuntu-latest)	3m 15s
build (supported)	3m 21s
build (latest)	3m 19s
quick-build (dev, ubuntu-latest)	3m 15s
build (dev, --warnings)	3m 22s
doc-coqdoc	1m 26s
doc-alectryon	15m 14s
coqchk (supported)	2m 4s
doc-dep-graphs	7m 28s
doc-timing	2m 0s
coqchk (latest)	2m 1s
coqchk (dev)	1m 53s
install (supported)	1m 34s
install (latest)	1m 38s
install (dev)	1m 40s
deploy-doc	0s
delete-artifacts	5s
	1h 13m 23s

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