After rebasing my Flow upgrade stack, I noticed a bunch of new errors: https://gist.github.com/Ashoat/b83564168fda704b2ce9d8051d0f472e
I played around a bit and it seems like an incompatibility between `CryptoKey` and `SubtleCrypto$JsonWebKey` introduced in D9535 and D9661, [here](https://github.com/CommE2E/comm/blob/5d8bb1971abeead06d3f73c8e33ab3c2101280e8/web/account/account-hooks.js#L232-L237) and [here](https://github.com/CommE2E/comm/blob/5d8bb1971abeead06d3f73c8e33ab3c2101280e8/web/push-notif/notif-crypto-utils.js#L53-L63).
One potential solution is to consider that perhaps our type (`CryptoKey`) should actually be the built-in type `SubtleCrypto$JsonWebKey`. This diff proposes that, but it will need a close review, as I'm not confident at all in this assessment.
NOTE: CI will fail on this diff. I considered the possibility of fixing Flow errors BEFORE upgrading Flow, but it wasn't possible... in some cases, the fixes to support the new version of Flow caused errors in the old version. I could have hidden these type errors with `$FlowFixMe` lines and then later revert those, but that seemed like too much busy work.
Depends on D9786