TLS 1.3 cipher suites can't be customized

[wkornewald]

This is mentioned in the CAPABILITIES.md, but I'm not sure if this is considered a bug or not. For us it's a bug because we have to go through a security admission process for medical software and ChaCha20 is not accepted (which may be absurd, but it's just the way it is). So, we can't get our app through the admission with Conscrypt and have to switch to a different solution. It would be much nicer, though, to be able to use the standard solution - which is Conscrypt.

Could you please make the TLS 1.3 cipher suites customizable, so our configuration doesn't get silently ignored?