revert subtype theory + syntactic sugar for cloning it #3637

Job	Run time
EasyCrypt compilation (nix)	40s
EasyCrypt compilation (opam)	2m 45s
Fetch EasyCrypt External Projects Matrix	5s
Check EasyCrypt Libraries (unit)	2m 49s
Check EasyCrypt External Projects (jasmin-eclib, https://github.com/jasmin-lang/jasmin, main, ecl...	3m 27s
Check EasyCrypt Libraries (stdlib)	6m 23s
Check EasyCrypt External Projects (sha3, https://gitlab.com/easycrypt/sha3, next, ., config/tests...	14m 0s
Check EasyCrypt Libraries (examples)	4m 27s
Check EasyCrypt External Projects (cryptobox, https://gitlab.com/fdupress/ec-cryptobox, next, ., ...	3m 47s
Check EasyCrypt External Projects (xsalsa20, https://gitlab.com/fdupress/ec-xsalsa, master, ., co...	3m 7s
Check EasyCrypt External Projects (xmss-acai, https://github.com/MM45/FV-XMSS-EC, master, ., conf...	8m 6s
Check EasyCrypt External Projects (xmss-fsai, https://github.com/MM45/FV-XMSS-EC, master, ., conf...	7m 41s
Check EasyCrypt External Projects (sphincsplus, https://github.com/MM45/FV-SPHINCSPLUS-EC, master...	20m 12s
Check EasyCrypt External Projects (set-status)	3s
Notification	5s
	1h 17m 37s

Provide feedback