Add chevron to clickable WarningItem on Android

[DRadmir]

Summary

• Show a trailing chevron on WarningItem when it has an onClick, making the tap affordance explicit on confirm-screen errors (e.g. Bitcoin dust error).
• Chevron is vertically centered relative to the title + message column so it stays aligned whether the warning is one or two lines.
• Non-clickable callers (SimulationWarningsContent) are unaffected — the chevron only renders when onClick != null.

Test plan

• ./gradlew :ui:compileDebugKotlin
• ./gradlew :features:confirm:presents:compileDebugKotlin
• Visual check on confirm screen dust error