feat(settings): add desktop Timeout and cancel card
Because: - We are updating pairing flows and want to land UI components / pages first. - Adds the desktop screen shown when pairing times out or is canceled. This commit: - Adds `packages/fxa-settings/src/pages/Pair2/Authority/TimeoutAndCancel/index.tsx`, one presentational card covering both the `timeout` and `canceled` reasons. - Adds per-variant Fluent strings, Storybook stories, and unit tests. Closes #FXA-14241