Keep track of changes related to the release of CH EMED 4.0.0 to report to integrators

[dvribeira]

Relevant changes (i.e. not just description fixes) following the adaptation of CH-EMED-EPR to the final 4.0.0 version of CH EMED and of interest to integrators should be compiled for instance in this issue so that a digest can be provided to them. For instance all the IG changes related to authorship fields covered by #39.

[dvribeira]

• Authorship and timestamps.
• Changes in UnitCode valueset
• Removed N from CHEMEDEprActSubstanceAdminSubstitutionCode
• This was already the case for the deployed aggregator logic, but the IG now reflects that the dispense .prescription extension is supported and that it is indeed mandatory if the treatment has already been prescribed. This check is not done by the FHIR validator but by the PMP's business logic.
• .note changes/alignment check coherency of note.time #37
• Constrain the observation medicationStatementChanged and medicationRequestChanged extensions to use the CH EMED EPR profiles #47
• PRE: .dispenseRequest and validityPeriod become optional Changed PRE validityPeriod to be optional. #49

[dvribeira]

A digest of relevant changes is being kept up to date here: https://cara-ch.github.io/emed-service-guide/other/upcoming_changes/