New PATCH endpoint on DataController to both save changes and run validation

[ivarne]

For continuous validation on all save operations we need a new endpoint that both saves and runs relevant validations so that frontend can keep an updated list of backend validation issues without running expensive validations too often.

Requirements

• Validators must get info about what has changed, so that they can be skipped and frontend keeps the old issue list for that validator.
• DataProcessor must get info about changes, so that expensive calculations/api calls only runs when required.

Nice to have

• Multiple users on the same app instance does not always cause a race condition and lost data.
• Reduce data sendt over the wire

Proposed solution

New endpoint that uses JSONPatch to describe the changes that needs to be made to the data model. This means that we first need to read the old data from storage before applying the patch and storing the updated data.

In addition we take a list of validatorId that frontend knows that it does locally, so the server kan skip running those validators (until at the last validation).
The patch can be leveraged by validators to skip running when no fields relevant to the validator has changed and the issues list should be the same as before validation.
DataProcessing gets a view of the old model so they can do comparisons if they want to save on calculation time.