Improve support for RTL languages

[motinis]

When writing in an RTL language on iOS, mixing in any English words results in a complete mangling of the formatting. English should be “embedded” LTR within the RTL text.

[chrisbobbe]

Hi @motinis, welcome! This repository is in maintenance mode.

I'd like to invite you to try the next-generation Zulip iOS app, which is currently in beta and will replace the current app: https://testflight.apple.com/join/Q7dz4SHm

If RTL support is lacking there, please open an issue in https://github.com/zulip/zulip-flutter or start a discussion in the Zulip development community. 🙂