Refurbish IPAllow with libswoc.

[SolidWallOfCode]

Update IPAllow with libswoc, removing any dependence on the precursor utilities. This also removes support for the original format, leaving YAML as the only valid format.

To integrate Errata, I needed to move the diagnostic levels to plugin accessible header file. I am unwilling to create additional circular dependencies by making fundamental libraries (such as "tscpp/util") dependent on higher level libraries ("Diags"). One of the changes in Errata between the old and libswoc versions is this ability to adapt Errata to local error severities.

There was a bit of cleanup in libswoc for this, which is currently mixed in. Before this becomes a ready PR, I will cut a new release of libswoc and merge that in.

The IPAllow config was changed to use a MemArena because I think overall it's easier. The use of std::vector meant the records couldn't be directly stored during parsing, because a re-allocation of the vector would scrozzle the pointers, but I didn't want to separately allocate all of them. MemArena means these can be cheaply allocated and stored as parsed without a funky fix up later. At that point there's a bit of additional work to put all of the config data in the arena so there is no cleanup.

I got tired of dealing with optional pairs of addresses (IPv4 and/or IPv6) and added some classes to deal with that more cleanly. That could be split out in to a separate PR.

See this libswoc PR.

[brbzull0]

Looks good to me, I need this changes in for my records.yaml support.
The only think I don't like but you will be fixing is that we have swoc changes in here.