This PR adds a new setting to the config: `network.timeout`. This setting
defines a time period during which all handshake procedures and
ceremonies must be completed. If not - connection is aborted. This
should help in situations when connection is established but client
cannot continue for some reason (for example, RST sent by some middle box).

DPI bypass tools like ByeDPI fragment a single TLS record into multiple
records to evade censorship. This broke ReadClientHello because it
assumed the entire ClientHello arrives in one TLS record.

Add reassembleTLSHandshake that reads continuation records and
reconstructs a single TLS record before parsing and HMAC verification.
Per RFC 5246 Section 6.2.1, handshake messages may be fragmented
across multiple records — this is valid TLS behavior.