fix(chatform): sanitize the toxstring to remove characters after the \0

[nickolay168]

In Qt6 when we convert QByteArray to string, \0 is considered as a valid character and do not end the string. Some messengers as TRIfA may provide additional information after the 0-th symbol, resulting in unexpected output of non readable symbols.
By default TRIfA v3 message will have the next structure:
message
2 bytes \0 (guard)
32 bytes of random values
4 bytes timestamp
See source
In This PR we are adding option to hide this line, or show it (the content of the line is saved in chat history).

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[iphydf]

I don't think we should do this. Getting this right is tricky, because as implemented in this PR, this allows users to add secret messages behind a \0 that only some clients can read and qTox hides from its users. That's particularly relevant in group chats.

[nickolay168]

I don't think we should do this. Getting this right is tricky, because as implemented in this PR, this allows users to add secret messages behind a \0 that only some clients can read and qTox hides from its users. That's particularly relevant in group chats.

Yes, that sounds right. But how we should handle the TRIFA messages as they will merely always contain symbols after \0? Or may be, we can create an option in UI?

[iphydf]

Yeah, and maybe we can find out what format it's sending and make that option more specific so it filters out trifa stuff, not just anything after \0. Also we should still display something (like a coloured [...] to let users know there's something there. Then when the user disables the option (and restarts), the text should be there again, similar to the style options.

[nickolay168]

Yeah, and maybe we can find out what format it's sending and make that option more specific so it filters out trifa stuff, not just anything after \0. Also we should still display something (like a coloured [...] to let users know there's something there. Then when the user disables the option (and restarts), the text should be there again, similar to the style options.

I have added the new option and corresponding tests, sorry it took so long :)

[iphydf]

Is it actually TRIfA-specific? Can we call it something more generic, like post-null suffix or something?