Add Emulation for other Covenant Primitives?

[JeremyRubin]

If there were specs for other types of covenant gadget (not just the primitive, some application), it'd be possible to have Sapio demonstrate it's use with a signing oracle that exactly replicates the logic. In order for this to work, we'd need:

Requirements:

• [ ] Miniscript support for extensions (or allow non-miniscript leafs?) (cc @sanket1729 )
• [ ] Another covenant primitive to support (cc @ajtowns @roconnor-blockstream -- what might be relevant to emulate?)
• [ ] Interesting contracts...

The emulator spec can be based on https://learn.sapio-lang.org/ch05-01-ctv-emulator.html

[ajtowns]

Couple of introspection ideas I think are interesting:

• unilaterally remove yourself from a payment pool (ie, n members of a pool with a balance b_i each; t=sum(b_i); n-of-n signature allows spending t, single signature by i allows spending b_i, provided t-b_i becomes spendable by (n-1)-of-(n-1) signature of remaining participants, etc). ie, OP_EVICT, TLUV
• temporarily claim a script puzzle: take an arbitrary puzzle X, eg "2DUP EQUAL NOT VERIFY SHA256 SWAP SHA256 EQUAL", and lock B btc up conditional on it. have the rule be "you can spend the utxo to "P CHECKSIGVERIFY X" provided the output value increases to 1.05*B, and there's a recursive escape conditional on "288 CSV". ie: you can lock the puzzle up to being only claimable by your own pubkey for 2 days, as long as you stake 5% of the balance; then you reveal your solution to the puzzle after the lock up has confirmed, without randos being able to steal your solution and claim it as MEV.

[ProofOfKeags]

I think this will in general depend on #100 since we will want to consolidate how we do emulation into the SIMP system prior to extending the set of emulators.