TLS: Initial support for printing TLS PDUs

[ryandoyle]

Supports printing plain text parts of TLS. Basic record layer printing is supported as well as more complex printing of handshake and alert protocols, specifically ClientHello and ServerHello - these will print interesting parts of TLS extensions like ALPN, SNI and the underlying TLS version negotiated.

As we don't keep state and TLS is stateful, this printer does assume/ is limited by this, specifically:

• TLS version is printed as per record layer version. In the case of TLS 1.3, the record layer is set to TLS 1.2, and the supported_versions extension is used to negotiate the actual version used.
• Alert and Handshake protocol messages can be plain text or encrypted, depending on if a crypto context is established. This printer doesn't know this, so we try to detect it and print "(likely encrypted)".

[infrastation]

Thank you for preparing these changes. Apparently, uint does not belong to the Windows C compiler vernacular. The type needs to be either u_int or unsigned.

[ryandoyle]

Cheers @infrastation, fixed :+1: