MINIFICPP-1846 - Json configuration support part 1

[adamdebreceni]

:warning: To preserve you sanity during review diff the old YamlConfiguration.h to the new StructuredConfiguration.h, similarly do so for YamlConfiguration.cpp and StructuredConfiguration.cpp as git could not keep track of the lineage. Testing will happen in a separate PR as there will be some semantic changes to yaml parsing, better to keep those separate from this (mostly) syntactic change.

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