modify contract with yield/resume

[ppca]

now that yield/resume is on testnet, we should modify our contract and test it out on dev.

[ChaoticTempest]

There's no clear timeline on when it will make it to mainnet, so we might want to punt this until there's a clear timeline. That way we don't have this on testnet but have to wait for it to be on mainnet to actually go mainnet on our MPC network.

Ahh wait, it's going to be with regular release cadence so expected June 10th. Then yeah guess we should implement this sooner than later just so we don't have to deal with contention on the contract

[volovyks]

We should keep the old recursive design and add a new yield function to stay flexible with our release date.
Currently, this issue is blocked by Near SDK updates.

[volovyks]

NEAR SDK updates were merged. We can start working on this.
Saving a recursive design is unnecessary if the new yield/resume is stable.