feat(workspace): support object config

[dsherret]

This adds object config for the workspace config:

{
  "workspace": {
    "members": ["./member-1", "./member-2"]
  }
}

This is a more verbose version of "workspace": ["./member-1", "./member-2"]. Although we don't need it at the moment, it makes the naming of "workspace" more clear and leaves the object open for more config in the future.

Closes #24456

[bartlomieju]

LGTM