Gutenberg: Allow for block pattern in Widget Screen

[bph]

It seems with the omission of the widget title property of widgets, and the replacement of the current core widgets with blocks, that don't have titles, end users will need to use multiple steps to recreate their sidebar units, combining core/block like latest posts or calendar with a heading block (=title) to display in the sidebar.

Now that every block has its widget wrapper this seems to only work well with a group block containing heading block + paragraph block.

With block patterns available via the Inserter, themes and plugins would be able to provide the widgets as a block patterns and help their users with this.

[annezazu]

@mapk wanted to flag this for you for a design perspective as this seems like a major UX flow to get right.

[mapk]

Thanks for the ping, @annezazu! Overall moving to blocks and helping users become accustomed with blocks is our goal here.

Block patterns can help as @bph points out when trying to combine blocks, or even just trying to establish a nice layout. I'm all for this. I remember @justintadlock pointing this out too.

Currently, we've just merged in Reusable blocks. Let's get a Patterns tab in there now too.