revert subtype theory + syntactic sugar for cloning it #3629

Job	Run time
EasyCrypt compilation (opam)	1m 21s
EasyCrypt compilation (nix)	1m 21s
Fetch EasyCrypt External Projects Matrix	4s
Check EasyCrypt Libraries (unit)	1m 32s
Check EasyCrypt Libraries (stdlib)	4m 57s
Check EasyCrypt External Projects (jasmin-eclib, https://github.com/jasmin-lang/jasmin, main, ecl...	1m 57s
Check EasyCrypt Libraries (examples)	3m 5s
Check EasyCrypt External Projects (sha3, https://gitlab.com/easycrypt/sha3, next, ., config/tests...	11m 39s
Check EasyCrypt External Projects (cryptobox, https://gitlab.com/fdupress/ec-cryptobox, next, ., ...	2m 30s
Check EasyCrypt External Projects (xsalsa20, https://gitlab.com/fdupress/ec-xsalsa, master, ., co...	1m 48s
Check EasyCrypt External Projects (xmss-acai, https://github.com/MM45/FV-XMSS-EC, master, ., conf...	1m 36s
Check EasyCrypt External Projects (xmss-fsai, https://github.com/MM45/FV-XMSS-EC, master, ., conf...	1m 38s
Check EasyCrypt External Projects (sphincsplus, https://github.com/MM45/FV-SPHINCSPLUS-EC, master...	2m 7s
Check EasyCrypt External Projects (set-status)	4s
Notification	0s
	35m 39s

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