Consolidate "Attestation", "Exchange", and "Query" into one IG

During ballot review I was overwhelmed trying to flip back and forth among:

• http://hl7.org/fhir/us/directory-attestation/2022Sep/
• http://hl7.org/fhir/us/directory-exchange/2022Sep/
• http://hl7.org/fhir/us/directory-query/2022Sep/

Content is largely duplicated across these guides, with small differences in the background information that are very difficult to find. With layered profiles, flipping between IGs to track down definitions is also difficult, and does not provide any obvious benefit. 

The content from all three IGs should be combined into a single IG. There can still be distinct profiles and capability statements for query vs exchange vs attestation when needed, but the overviews and explanations should be de-duplicated and presented in a logical flow. In addition to benefits in readability, consolidating these IGs would make it easier to manage changes as well.