feat(settings): add mobile Ready to scan card
Because: - We are updating pairing flows and want to land UI components / pages first. - Adds the mobile screen telling the user how to start pairing from their computer. This commit: - Adds `packages/fxa-settings/src/pages/Pair2/Supplicant/ReadyToScan/index.tsx`. - Adds storybook stories and tests for the page. - Adds l10n files. Closes #FXA-14237