code refactor: CommandResult.Error needs real fields not a map

[amorton]

after the work in #1454

it's clear now we have a better view on what an error should be, from Error Object v2 work, and the CommandResult.Error is a hot mess with a map of values that is expeded by jackson

• refactor so we have fields on the record for all the expected fields of an error object
• work out how to have the JSON serialisation ignore that fields that are either not set, or we dont want to send. The hard part will be that the "scope" field is optional for error object v2. But maybe we just make sure Jackson excludes fields that are null, and we make sure to set scope to empty string (which I think already happens)

this will have a wide impact in the code base

[amorton]

Partially addessed in #1447

it adds CommandErrorV2 class that is used for the warnings, this ticket is now to change the code for errors to use that class and its CommndError (v1) parent whenneeded.