Wire up verification cancel & mismatch for rust crypto

[t3chguy]

Fixes element-hq/element-web#27394

[richvdh]

Thank you for picking this up, though it makes me very uneasy that we don't have a test (preferably an end-to-end one, using playwright) for this. The lack of tests is why we have all these rough edges in the first place :(.

[t3chguy]

Fair, I did test it myself, can I sign a deed poll to rename myself to Mr. Playwright or does that not count?

[richvdh]

The change looks plausible

[t3chguy]

I'll add a boring old automated Playwright test on matrix-org/matrix-react-sdk#12526

[richvdh]

FWIW, there's also a not-bad suite of Jest tests for verification at the js-sdk level in spec/intec/crypto/verification.spec.ts, which would also be nice to extend. But given a choice between that and a playwright test, I'd probably prefer the playwright one.

[t3chguy]

Playwright test wired, had to disable it for legacy crypto as that doesn't show the expected mismatch modal and only shows the cancelled state as it does not set the cancellationCode as expected. Given its legacy and hopefully being ditched soon I don't think its worth digging into further.

[andybalaam]

Nice, thank you t3chguy!