#2901 Add support for overflow to POCOs

[ewoutkramer]

Description

This PR is the first shot at adding support for overflow to POCOs. It should not introduce major breaking changes.

Remarks

⚠️ I had introduced the this[] operator for setting values, as we already had a getter for it hidden behind IReadOnlyDictionary. This meant that an existing this[] operator on the Parameter resource had to be removed as it conflicted with this operator in Base. Later I implemented this operator explicitly, so the problem does not exist anymore, but just for future flexibility I am removing this minor feature. This is a breaking change.

⚠️ Since pocos now implement IDictionary, they implement ICollection, which triggered bugs since we used a comparison to ICollection<T> to detect whether an element repeated or not. I changed the method in ReflectionHelper to detect IList<> instead. This is a breaking change.

⚠️ Also review and pull FirelyTeam/fhir-codegen#42, which are the changes to the codegen necessary to produce POCO's for this PR.

Related issues

Fixes #2901.

[ewoutkramer]

error CP0002: Member 'Hl7.Fhir.Model.Parameters.ParameterComponent Hl7.Fhir.Model.Parameters.this[string].get' exists on [Baseline] lib/net8.0/Hl7.Fhir.Base.dll but not on lib/net8.0/Hl7.Fhir.Base.dll [D:\a\1\s\src\Hl7.Fhir.Base\Hl7.Fhir.Base.csproj]

Use GetSingle() instead.

[ewoutkramer]

error CP0002: Member 'bool Hl7.Fhir.Utility.ReflectionHelper.IsTypedCollection(System.Type)' exists on [Baseline] lib/net8.0/Hl7.Fhir.Base.dll but not on lib/net8.0/Hl7.Fhir.Base.dll [D:\a\1\s\src\Hl7.Fhir.Base\Hl7.Fhir.Base.csproj]

Use IsListCollection(). instead

[Kasdejong]

There are too many things I want to comment on to do this via PR comments. Not because it's bad, but because I have not worked on this so I do not know what complications impacted your design :) We should discuss in person or over slack.