Update CodeSystem-UKCore-FundingCategory.xml

[ryma2fhir]

From #550 (comment)

If we are going for a breaking change, I would then prefer Public/Private being the parent concepts with NHS England, NHS Wales, NHS Scotland, HSC Northern Ireland, NHS Isle of Man, Jersey, Guernsey and possibly Overseas Visitor under public. (As this field is meant to represent how the test is being funded, rather than where the test is taking place)

The current version of the codesystem does not match its intended use. Happy to use the codesystem as is for the purposes of the Genomics Alpha but, if possible, this should be changed in future releases

[ryma2fhir]

@omarisgreat @KazeemHamzat - Is this the way you expected the Funding CodeSystem to look?

[omarisgreat]

Also just noticed, the ConditionBodyStructure extension (structuredefinitions/Extension-UKCore-ConditionBodyStructure.xml) references a UK Core Condition, when it should reference a BodyStructure resource. Not sure if you want to bring this into this PR or add a new one