* Lock the LinkNewDeviceScreen to portrait.
* Add cancel buttons to the QR Code errors and handle cancel/startOver correctly.
* Use the shared QRCodeErrorView in the LinkNewDeviceScreen.
* Clarify the different QR Error/ErrorStates a bit more.
* Update snapshots.
* Replace GrantLoginWithQrCodeHandlerSDKMock with LinkNewDeviceServiceMock.
Add tests for all initial states on the QRCodeLoginScreen.
* Add tests for linking both mobile and desktop devices.
* Add UI tests for linking a new device.
* Don't show the Link Desktop Computer button when running on macOS.
This mirrors the decision to hide the Sign In With QR Code button on the start screen.
* Adds the remaining parts for showing/scanning a QR code to link a new device.
* Refactor the QRCodeLoginService to work the same way as the LinkNewDeviceService.
* Add a LinkNewDeviceService that exposes the SDK's grant QR code login methods.
* Add a flow coordinator for linking a new device.
Changes the presentation too.
