Expose Block Grid Group Aliases to queries

[deanleigh]

I hope I am using the correct terminology.
We have the ability to create groups within the block grid data type.
Typically I would create a group for layouts and another group for features which I think is something I discuss with HQ very early on in the development of block grid and that seems to be the way most examples have been created.

Example
I wanted to apply a style only to Layout Blocks

However there did not seem an off-the-shelf way to get the Group alias.
So @prjseal wrote an extension so we could get it in UmBootstrap but can it be included by default please?

Pauls example:
https://github.com/UmTemplates/UmBootstrap/blob/develop/Umbootstrap.Web/Extensions/PublishedContentExtensions.cs