SAS verification can end up as a success even though the SSK signature is never uploaded

Nobody has claimed this yet.

## What is happening

- There is an existing device `A`
- The user wants to login a new device `B`

Device `B` starts an emoji verication with `A`
At the end of the process:

`B` will mark is own identity as verified `OwnUserIdentityData::mark_as_verified`. This will just make it as locally verified.

Device `A`, as the existing device, is the one that is responsible of signing the new device `B` with the ssk and to publih the
signature to the home server.

If for any reason, device `A` fails to sign and/or to publish the signature:
- `A` lost network
- `A` is turned off
- `A` do not have the private SSK
- Home server is having issues

**Then** `B` will forever think it is verified.
**But** it is not! The signature was never published. Yet, `B` think all is ok.

Rageshake of this scenario https://github.com/element-hq/element-x-android-rageshakes/issues/10069
`B` was seen as unverified by everyone. EXA was not warning me

## Expected

As part of the verification process, device `B` should wait for the signature to be uploaded. I.e query it own key until it can see the verification signature published?

Start at OwnUserIdentityData::mark_as_verified and trace the emoji verification flow through the existing-device signing and signature publication steps. Check how device B observes its own key and verification state. Done means B is not treated as fully verified unless the SSK signature is visible on the homeserver, including when signing or publication fails.

Written by the indexing model from the issue text.