Adds secure renegotiation TLSX_Type, structure and enabler function.
Renames TLSX_Append to TLSX_Push, adding data param and making sure the list doesn't holds duplicate extensions.

Adds SecureRenegotiation functions
Renames TLSX_Append to TLSX_Push, adding data param and making sure the list doesn't holds duplicate extensions.

Adds SecureRenegotiation functions