Accessibility: Structure of creation UI type selection screen is not conveyed, each insight type is not in a group

[felixfbecker]

When going to https://sourcegraph.sourcegraph.com/insights/create?dashboardId=all to create an insight, each card is not in a group or list item, making it hard as a screen reader to understand what content is together in a card and represents an insight type. It also makes it harder to skip to later types.

/cc @Joelkw @felixfbecker @vovakulikov

[vovakulikov]

Related issue about the creation Intro page and its card types announcements https://github.com/sourcegraph/sourcegraph/issues/41793