Enable graph saved objects to be import / exportable.

[mikecote]

Once #34989 and #34862 are completed, graph saved objects can be enabled for import / export. Follow #34896 or upcoming docs to enable the feature.

[elasticmachine]

Pinging @elastic/kibana-app

[flash1293]

After syncing with @rudolf there is a workaround to solve it in a slightly hacky way just for Graph.

The thing to migrate is changing index patterns referenced by name to index patterns referenced by id.

Instead of migrating using the migration system, the Graph app inspects the saved objects if a user opens a workspace. If it is using the name reference, it will try to find the matching index pattern and fix the index pattern reference in memory. If the user saves the workspace, the updated version will get persisted.

There are a few edge cases (e.g. what if there is no matching index pattern), but the Graph app is planned to handle changes between index patterns anyway, so the logic to handle that will be available.

[shaunmcgough]

Joe are you comfortable with this approach? I would also consider the way Canvas handles this - as a JSON to import / export.

[flash1293]

@shaunmcgough I think it's the right thing here to integrate with the migration/import/export system as much as possible, gives the user a single place to manage these things.

Canvas also does this: