Events "Sent from an insecure device" are not updated when we receive the correct cross-signatures for the device.

Not sure of exact repro steps, but something like:

1. Receive a message from someone you haven't met before
2. Observe "Sent from an insecure device"
3. Check devtools, discover their device is in fact signed correctly.

The problem is that it can be a few seconds before we receive the user's identity, and we don't update the UI when that happens.

Specifically [this line](https://github.com/matrix-org/matrix-js-sdk/blob/c2f9ad28fc1e694931536bbe64b2d4757dc0eb34/src/rust-crypto/rust-crypto.ts#L2393) means that we don't attempt retries on events which fail due to "unsigned device". As a side note, the error message on line 2396 is misleading: `UnsignedSenderDevice` means it is the device that is not correctly cross-signed, not the identity.

We should probably consider the other error codes and decide if any of them need updates while we're in the area.