Input for special characters on web app

[Lagyamfi]

Add the possibility for user to in put special characters for local languages, if they are not available on the keyboard.
The first objective is to implement this on the web app.

An example of this feature is shown on the following website:
https://www.webonary.org/buli/

we are using the test server for now to try out the changes on the streamlit app. once all confirmed, we will port it to the public application.