PUT /incarnations/{id} no longer patches incarnations

[defreng]

The PUT incarnation endpoint was not behaving as a PUT endpoint should behave. So far, it was merging the provided template data / version with what was used for the previous change - instead of requiring completely specifying the desired state of that incarnation.

This behavior for example made it impossible to delete custom values for template variables and go back to using the default value.

Changes

• PUT /incarnations/{id} no longer patches the incarnation. Instead, a change will be created that only contains the data from the request
• for patching (e.g. only updating the template version, without changing the template data values), a new PATCH /incarnations/{id} endpoint was created