ioc: fix dbLoadGroups command.

[ericonr]

Calling GroupConfigProcessor().loadConfigFiles() reads and clears config.groupConfigFiles, and loads the JSON files before iocInit. When loadConfigFiles() is called again from an init-hook, config.groupConfigFiles is empty, and no JSON files are actually read, so no groups in those files are loaded.

This change removes error messages at the point where dbLoadGroup is called; errors are now displayed only during iocInit.

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Fixes #88

I would like to add tests before merging this. Done!

I think I mostly understood what caused this problem, but I couldn't find where config.groupMap is cleared before/during iocInit, so I didn't understand why loadConfigFiles() before iocInit was an issue.

I'm assuming groupConfigFiles is cleared by std::move (this seems to be a correct assumption), but if there's some spot that simply clears the whole config, it might simply be cleared along with groupMap.

[mdavidsaver]

Thanks for figuring this out. Merged as of 8502f91 with some changes.

wrt. 28817ae New test data files need to be appended to the TESTFILES Make variable to be captured during build and made available when tests are run on an embedded target.

8502f91 adds an IOC state check to dbLoadGroup() to catch accidental calls after iocInit(), when it would not have effect.

[ericonr]

Cheers, thank you for merging and fixing the necessary parts :)