This commit updates our transport settings for 7.0. It generally takes a
few approaches. First, for normal transport settings, it usestransport.
instead of transport.tcp. Second, it uses transport.tcp, http.tcp,
or network.tcp for all settings that are proxies for OS level socket
settings. Third, it marks the network.tcp.connect_timeout setting for
removal. Network service level settings are only settings that apply to
both the http and transport modules. There is no connect timeout in
http. Fourth, it moves all the transport settings to a single class
TransportSettings similar to the HttpTransportSettings class.
This commit does not actually remove any settings. It just adds the new
renamed settings and adds todos for settings that will be deprecated.