Redesign the 'install profile selection' installer screen to allow for experimental profiles and more information

Problem/Motivation

As part of #2809635: Create experimental installation profile → we intend to add an experimental profile for Drupal 8.
This profile will be different to the other profiles in core in so far as its more of a finished product than a starter kit.
Or to use the Lego analogy, its a Police Station set, instead of a bucket of bricks.

At present the installer's 'select profile' screen doesn't really facilitate communicating this type of information.

Proposed resolution

Redesign the 'select profile' screen to include additional functionality - possibly including

• The ability for profiles to provide a screenshot/thumbnail/logo - like themes can
• A default logo - for profiles that don't provide one - my thinking is this should look like the module icon we have in the toolbar, i.e. a 'generic starter kit' building block, but I'm not a designer
• Grouping into 'starter kits' and 'fully featured products' (exact naming to be confirmed)
• A treatment for experimental profiles to indicate they aren't yet stable - this might include their alpha/beta status or might just be a label 'Experimental'

Remaining tasks

Come up with the design.
Implementation is a separate issue.

User interface changes

New installer screen design.

API changes

Possibly new keys available in profile's .info.yml (not in this issue).

Data model changes

None