[Dashboard] Make Dashboard Saved Object share-capable

[crob611]

Dashboard Saved Object is currently nameSpaceType: single. It should be updated to multiple_isolated per #100489

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[jportner]

Note that this also entails changing the client and server API calls to use the new savedObjectsClient.resolve() API (instead of savedObjectsClient.get()), and handle the three different outcomes ('exactMatch', 'aliasMatch', and 'conflict'). See more details in the linked meta issue #100489.

[jportner]

In case anyone is following this issue but not the linked meta-issue (#100489):

I published the Sharing Saved Objects developer guide, please take a look before proceeding with the implementation. And of course, please reach out if you run into any problems!

[jportner]

@crob611 just to let you know, making this change will cause Spaces API integration tests to fail. The same thing is happening for index patterns, see here: #114408 (comment)

When you get a PR up for making dashboards share-capable, tag me and I will push a commit that fixes the integration tests for you 👍

[jportner]

Hey @crob611 I just wanted to check on the status of this to see if it's on track for the 8.0 release; as mentioned above, I suspect the change will cause some Spaces integration tests to start failing, and I'll need to help you fix that