revert subtype theory + syntactic sugar for cloning it #3634

Job	Run time
EasyCrypt compilation (nix)	1m 19s
EasyCrypt compilation (opam)	2m 44s
Fetch EasyCrypt External Projects Matrix	2s
Check EasyCrypt Libraries (unit)	2m 55s
Check EasyCrypt External Projects (jasmin-eclib, https://github.com/jasmin-lang/jasmin, main, ecl...	3m 30s
Check EasyCrypt Libraries (stdlib)	6m 26s
Check EasyCrypt External Projects (sha3, https://gitlab.com/easycrypt/sha3, next, ., config/tests...	14m 22s
Check EasyCrypt Libraries (examples)	4m 35s
Check EasyCrypt External Projects (cryptobox, https://gitlab.com/fdupress/ec-cryptobox, next, ., ...	4m 1s
Check EasyCrypt External Projects (xsalsa20, https://gitlab.com/fdupress/ec-xsalsa, master, ., co...	3m 10s
Check EasyCrypt External Projects (xmss-acai, https://github.com/MM45/FV-XMSS-EC, master, ., conf...	8m 21s
Check EasyCrypt External Projects (xmss-fsai, https://github.com/MM45/FV-XMSS-EC, master, ., conf...	7m 33s
Check EasyCrypt External Projects (sphincsplus, https://github.com/MM45/FV-SPHINCSPLUS-EC, master...	20m 9s
Check EasyCrypt External Projects (set-status)	1s
Notification	4s
	1h 19m 12s

Provide feedback