Arabic Translation for `dcrtimegui`

[Insaf01]

This pull request adds a complete Arabic translation for the dcrtimegui interface, aimed at enhancing accessibility for Arabic-speaking users. The translation covers all elements in the src/i18n/translations/en.json file.

While functional, this initial version may have minor rendering issues due to right-to-left text orientation. I plan to collaborate with the developers in the Decred community for necessary adjustments in future updates.