Enable ClientHello Segmentation: allows the ClientHello packet to be sent by...

Enable ClientHello Segmentation: allows the ClientHello packet to be sent by segmenting it into multiple packets (#2403).

Can be useful for circumventing censorship via DIP introspection.
The patch automatically disables the mode in case of outdated or incompatible servers, if the TLS handshake fails or times out.
The mode is accessible via the flag clienthello-fragmentation and is currently disabled.