VONK-5300 Accessing the Definition when visiting all descendants of a ITypedElement

[louisledev]

Description

Add an access to the Definition property when visiting all descendants of a ITypedElement in order to detect element with an invalid definition .
Background for this PR: In Vonk, for the patch operation, we create a PartToElementAdapter (see https://github.com/FirelyTeam/Vonk/blob/0b352a37b8d717b4c590622dc5d89347670e5c54/src/Vonk.Core/ElementModel/FhirPatchedElement.cs#L176) with the field to patch. In case of a non-existing field for the resource type to be patched, when getting the definition of the element, we get an exception. So, as part of the prevalidation for the patch operation, we would like to check that both the value but also the definition of all the PartToElementAdapter are valid.
see PR fixing the issue locally in VONK: https://github.com/FirelyTeam/Vonk/pull/1300

Related issues

VONK-5300

Testing

Tested using Firely Server. See https://github.com/FirelyTeam/Vonk/pull/1300

FirelyTeam Checklist

• Update the title of the PR to be succinct and less than 50 characters
• Mark the PR with the label breaking change when this PR introduces breaking changes

[marcovisserFurore]

We think this change will have a big impact on the performance for our existing and future users. We understand that this issue is a problem for the Firely Server, but maybe we can come up with a different solution with less impact. See the added issue here.