[Locale] Support Arabic language

[okerx]

Summary

I'm building an App with Toolpad that supports Arabic language. Arabic is my first language so I'm happy to open a PR for it.

Examples

No response

Motivation

No response

Search keywords: Arabic language locale

[bharatkashyap]

Feel free to open a PR to add a new locale here: https://github.com/mui/toolpad/blob/master/packages/toolpad-core/src/locales/hiIN.tsx

On the lines of #4775

[JAugustusSmith]

Should it use the full culture code or just the language part? I made a bunch of translations based on the language part, so I didn't have a separate language for en-AU, en-US, en-gb, I just made one for en

[bharatkashyap]

Just the language file, as was done in the PR I mentioned above