[FieldTypes] Getting rid of IFieldInfoValue in favor of TaxonomyFullValue.
- Eventually, TaxonomyFullValue could also replace the good old TaxonomyValue. For the time being, while we get the converters sorted out, let's keep them separate.
- TermGroupInfo and TermSetInfo have their parent in their properties, instead of listing their children. Thanks to this, from TermInfo you can navigation all the way up to the TermStoreInfo object.
- TaxonomyContext takes care of summarizing this ParentTermSet -> ParentTermGroup -> ParentTermStore chain AND also it documents the TermSubset limiting term (optional) parameter (to limit choices under a specifc term in the term set)