Add TCP, TCPDNS and TLSDNS write timer

Add TCP, TCPDNS and TLSDNS write timer

When the outgoing TCP write buffers are full because the other party is
not reading the data, the uv_write() could wait indefinitely on the
uv_loop and never calling the callback.  Add a new write timer that uses
the `tcp-idle-timeout` value to interrupt the TCP connection when we are
not able to send data for defined period of time.