Rewrite add_analyzer script to C++

[mikepurvis]

As part of our Python 3 migration, the add_analyzer script has come up as a nuisance which would be nice to avoid. Given that the rest of this package is C++, how would we feel about rewriting the script to be a small binary and parameterizing the service name?

The main proviso is that it would still need to shell out to rosparam path/to/my.yaml /namespace to perform the yaml loading, so the startup cost of running that Python program would be paid, but not the memory cost of a long-running Python process.

If there's interest in this, I can send a PR.

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Memory size should probably not be a major consideration in this, but there is a slight savings— the python process at idle has a vsize of around 1MB, while the C++ version at idle is 400kb.