Change promise all into two separate calls.

[zajck]

Promise.all should be only used with static calls or when the order of transactions doesn't matter.

In the changed code, the order matters, since it influences the offer id. If the order is switched, the commit to offer in

boson-protocol-contracts/test/protocol/MetaTransactionsHandlerTest.js

Line 3714 in 1bc3375

await exchangeHandler.connect(buyer).commitToOffer(await buyer.getAddress(), offerToken.id);

failed about half of the time.

[coveralls]

coverage: 98.916%. remained the same
when pulling 1bc3375 on make-tests-deterministic
into f31a6a7 on main.