New `is_default_workspace` field

As part of a gradual multi-product migration, users will eventually be able to return the ID of the main workspace instead of null (read more here).

We added the is_default_workspace field to API versions 2024-04 and later to help identify which workspace is the main one. This field returns true if a workspace is the main one or false if it isn't.

query { workspaces { id is_default_workspace name } }