* Element-R: implement `{get,set}TrustCrossSignedDevices`
A precursor to https://github.com/vector-im/element-web/issues/25092
* Pull out new `DeviceVerificationStatus`
Define a new base class to replace `DeviceTrustLevel`. The intention is to have
a cleaner interface which is easier to expose from the new crypto impl
* Define, and implement, a new `CryptoApi.getDeviceVerificationStatus`
This is similar to `checkDeviceTrust`, which we're deprecating, but:
* is `async`, meaning we can implement it in Rust
* Returns a `DeviceVerificationStatus` instead of a `DeviceTrustLevel`
* Returns `null` rather than "not verified" if the device is unknown
* add some tests
* Export DeviceVerificationStatus as a proper class
... so that we can instantiate it in tests
* Send one time key count and unused fallback keys for rust-crypto
* Add tests
* Remove useless type in promise return
* Add test for one time key upload
* Fix rust-crypto.spec.ts tests
* Remove unneeded code in test
* Add key upload request test
* Fix tests
