Add support for getting the basemap group

[kellyhutchins]

Org users can opt-in to displaying vector basemaps so we should add support to check the self for vector basemap support and if there get the vector basemap group otherwise get the default basemap group.

[driskull]

@kellyhutchins doesn't the BasemapGallery widget do this already or is there plans to? What would the basemap group be used for?

[kellyhutchins]

@driskull there may be plans to do so but currently it doesn't read the org profile and use the specified group. The info would be used to pass in the group id to the Basemap Gallery or for apps that want to display or basemaps in some way.
I guess we could defer this one to see what future support is added but until then apps that use the BMG would need to query the self call themselves to get the info.

[driskull]

I think there are plans to do this so we may want to hold off. I think the plan is for most widgets to check the portal for info like this. That's what I've been hearing anyways.