[8.0 only] Make "map" saved object share-capable

[nreese]

As part of the sharing saved-objects in multiple spaces project, we need to convert "map" saved object type to share-capable / multiple-isolated namespace type in the 8.0 release (meta: #100489). This is required to enable us at a future time to support sharing our saved objects across spaces.

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)

[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!