Add logger roscpp_internal.connections.

To assist with troubleshooting, have added a DEBUG macro for
logging messages to the named logger roscpp_internal.connections.
We need more connection leve diagnostics in our logs but turning
on DEBUG for roscpp_internal generates a flood of information. We
only need visibility into when tcpros connections are created/dropped
for publishers and subscribers. The roscpp_internal.connections
targets those specific messages while still inheriting the log level
for roscpp_internal.

Merge pull request ros#2 from clearpathrobotics/NIM-2725

NIM-2725 Add logging around publisherUpdate and Inbound failures

Merge PR https://patch-diff.githubusercontent.com/raw/ros/ros_comm/pu…

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